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Cardiovascular Research 2001 51(3):577-584; doi:10.1016/S0008-6363(01)00283-8
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Copyright © 2000, European Society of Cardiology

Relaxant effect of C-type natriuretic peptide involves endothelium and nitric oxide–cGMP system in rat coronary microvasculature

Friedrich Brunner* and Gerald Wölkart

Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, A-8010 Graz, Austria

* Corresponding author. Tel.: +43-316-380-5559; fax: +43-316-380-9890 friedrich.brunner{at}kfunigraz.ac.at

Received 9 October 2000; accepted 14 March 2001


   Abstract
Top
 Abstract
1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 
Objective: Recent evidence suggests a possible role for nitric oxide (NO) in atrial natriuretic peptide-induced blood pressure effects. We tested the hypothesis that C-type natriuretic peptide (CNP)-mediated relaxation of the rat coronary circulation involves NO and activation of soluble guanylyl cyclase. Methods: Rat hearts (n=6 per group) were perfused in vitro at constant flow and the effect of CNP (0.1–3 µmol/l) on coronary perfusion pressure (a measure of vascular tone) and release of guanosine 3',5'-cyclic monophosphate (cGMP) was determined in absence and presence of the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (L-NNA; 0.2 mmol/l) or the natriuretic peptide receptor antagonist HS-142-1 (50 µg/ml). The involvement of Ca2+-gated and ATP-dependent K+ channels in CNP-induced relaxation was tested with iberiotoxin (30 nmol/l) and glibenclamide (1 µmol/l), respectively. Rings of rat aorta (n=12) were tested using the organ bath set-up. Results: CNP reduced perfusion pressure from 134±2 mmHg (baseline) to 71±1 mmHg (–48%) and this effect was significantly attenuated by L-NNA (–37%) or HS-142-1 (–19%). In presence of glibenclamide, CNP reduced perfusion pressure to 92±2 mmHg (–32%), in presence of iberiotoxin to 93±1 mmHg (–30% and in their combined presence to 102±2 mmHg (–23%) (P<0.05 vs. corresponding control). Basal release of cGMP was increased up to 4-fold by CNP and this increase was reduced (–50%) in presence of L-NNA or HS-142-1 (–68%). By contrast, relaxation of rat aortic rings mounted in organ baths was insensitive to inhibition by L-NNA. Conclusion: Relaxation of the coronary resistance vessels of the rat by CNP is partly mediated by the NO–cGMP pathway. These novel data support the existence of an endogenous link between soluble and particulate guanylyl cyclases in the control of natriuretic peptide-mediated coronary resistance vessel function.

KEYWORDS Blood pressure; Coronary circulation; K-ATP channel; Natriuretic peptide; Nitric oxide; Endothelial function; Endothelial receptors


   1 Introduction
Top
 Abstract
 1 Introduction
2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 
Atrial natriuretic peptide (ANP) is a potent cardiac hormone that regulates blood pressure, salt and water excretion and cell proliferation [1–3]. Another member of the natriuretic peptide family is C-type natriuretic peptide (CNP) which shares structural homology to ANP and occurs in several peripheral tissues including endothelial cells where its secretion appears to be regulated by local factors [4,5]. CNP is a potent venodilator and selective arterial dilator, but has only weak renal actions [5–7]. Therefore, CNP has been suggested to function as a paracrine factor in the control of vascular tone [6].

The mechanism of the vasorelaxant effect of natriuretic peptides is not fully understood. They appear to act by binding to membrane-associated members of the guanylyl cyclase coupled-receptor family (NPR-A and NPR-B) which consist of an extracellular binding domain and an intracellular catalytic domain (=particulate guanylyl cyclase) that bears close homology to soluble guanylyl cyclase [7]. ANP preferentially binds to the NPR-A subtype and CNP activates the NPR-B subtype [8]. Activation of receptors in cultured vascular smooth muscle cells or rat aortic rings by ANP or CNP results in an increase in intracellular guanosine 3',5'-cyclic monophosphate (cGMP), suggesting that the vasorelaxant effect is mediated by cGMP as a second messenger [9,10]. However, endothelial cells are also rich in binding sites and exhibit production of cGMP in response to ANP [11,12], but the functional consequences of endothelial receptor activation are not known. In this respect, one group has suggested that the vasodilator effects of ANP in the vasculature could occur in part through CNP production mediated by a guanylyl cyclase receptor on endothelial cells [13]. Another possibility is that the vasorelaxant activity of natriuretic peptides involves activation of endothelial NPR receptors, followed by the generation of endothelial nitric oxide and stimulation of smooth muscle soluble guanylyl cyclase [14]. The resulting increased production of cGMP would, similar to the cGMP produced by ANP through particulate guanylyl cyclase of smooth muscle cells, lead to a decrease in cytosolic Ca2+ levels and vasorelaxation through a series of intracellular events [15].

The purpose of the present study was to investigate the role of the endothelial NO–cGMP system in rat coronary resistance vessel relaxation in response to CNP. Coronary relaxation was documented as change in perfusion pressure in absence and presence of a NO synthase inhibitor, NG-nitro-L-arginine (L-NNA). The role of K+ channels in the relaxation response was tested with glibenclamide and iberiotoxin [16]. For comparison, a conduit artery (rat aorta) was studied using the organ bath set-up.


   2 Methods
Top
 Abstract
 1 Introduction
 2 Methods
3 Results
 4 Discussion
 5 Conclusion
 References
 
2.1 Heart perfusion
Hearts from Sprague–Dawley rats of either sex (300–340 g) were isolated and perfused with Krebs–Henseleit bicarbonate buffer via the aorta as previously described [17]. All animals received care in accordance with the Austrian Law on Experimentation with Laboratory Animals (last amendment, 1989) which is based on the principles of laboratory animal care as adopted by the American Heart Association and the Declaration of Helsinki. Hearts were equilibrated by perfusion at 67 mmHg and 37°C for 15 min. Then perfusion was changed to constant flow at 9 ml/min per gram wet weight and perfusion pressure was raised to ~130 mmHg (baseline) by adding endothelin-1 to the perfusion buffer (50 pmol/l, 15 min in recirculating mode). Endothelin-1 was used because of its proven role as a vasoconstrictor agent in resistance vessels [18]. For determinations of cGMP in coronary effluents, the buffer contained isobutylmethyl xanthine (IBMX; 1 mmol/l) to inhibit degradation of cGMP. It is unlikely that IBMX exerted any adenosine antagonism, because we observed a slight decrease (–8±1 mmHg), not increase, in baseline perfusion pressure.

2.2 Experimental protocol and inhibitory effect of L-NNA
Each heart was subjected to the following experimental protocol: (i) perfusion of CNP (final concentrations: 0.1, 0.3 or 3 µmol/l, via sideline), followed by (ii) perfusion of L-NNA to block NO synthase and (iii) repetition of phase (i). After each infusion, sufficient time was allowed for development of maximum relaxation and restitution of baseline pressure (10–15 min). L-NNA perfusion was at 0.2 mmol/l over 15 min in recirculating mode (total volume ~30 ml). Because L-NNA in itself raised perfusion pressure to ~120 mmHg, a lower dose of endothelin-1 (5 pmol/l, 15 min in recirculating mode) was used to generate the desired baseline perfusion pressure of ~130 mmHg. After 15 min of recirculation of L-NNA, perfusion was switched to non-recirculating mode and concentration response–curves for CNP were repeated in the continued presence of inhibitor (phase iii). In all experiments, indomethacin (10 mmol/l final concentration) was also coinfused to inhibit endothelial prostanoid production, which might confound the NO-related relaxation component of CNP.

2.3 Inhibitory effects of K+ channel blockers
To test the involvement of K+ channels in the relaxant effect of CNP [16], hearts were perfused as above with glibenclamide (1 µmol/l, 20 min) or iberiotoxin (30 nmol/l, 30 min) to block K+ATP and Ca2+-activated K+ channels, respectively. These interventions did not affect baseline perfusion pressure (Table 1). In separate experiments, the effect of combining both blockers was also tested.


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  		Table 1 Functional parameters in hearts treated according to the different protocolsa

 
2.4 Inhibitory effect of HS-142-1
We tested the effect of the ANP receptor ligand HS-142-1 [19] on CNP-induced vasorelaxation and effluent cGMP levels. This compound blocks both guanylyl cyclase-linked subtypes of natriuretic peptide receptors located on smooth muscle (NPR-A and NPR-B) and endothelial cells (NPR-B), respectively. HS-142-1 was added to the perfusate (final concentration: 50 µg/ml, equivalent to ~12 µmol/l) and recirculated for 10 min prior to testing the effect of CNP as described above.

2.5 cGMP measurements
Following application of CNP, coronary venous effluent was collected at two intervals (0–2 and 2–5 min) and stored at 6°C pending analysis of cGMP by radioimmunoassay. Standard curves were established in perfusion buffer containing 1 mmol/l IBMX and results expressed as nmol cGMP per liter effluent [17]. Because similar values were obtained for both time intervals, only results for 2–5 min collections are reported.

2.6 Organ bath experiments
Aortas were obtained from male rats, cut into rings with endothelium preserved, mounted in organ baths and analyzed as previously described [20]. Briefly, the tissues were equilibrated in Krebs–Henseleit bicarbonate buffer (90 min), precontracted with endothelin-1 (100 nmol/l) resulting in a mean tension of 5.2±0.30 g (n=12 rings). CNP was then added to the organ bath at 1–1000 nmol/l. L-NNA (0.2 mmol/l) was added together with the endothelin-1 for 15 min before CNP concentration–response curves were established. Addition of L-NNA negligibly increased vessel tone (0.2 g; 4% of developed precontraction, n=12). At the end of the experiment, the relaxant potency of nitroprusside (100 µmol/l) which activates soluble guanylyl cyclase, was determined for comparison. Drug concentrations are the final concentrations in the organ bath.

2.7 Drugs
CNP (1–22; FW 2197.6) was from Peninsula (Belmont, CA, USA); glibenclamide was from ICN Pharmaceuticals (Costa Mesa, CA, USA); L-NNA hydrochloride and iberiotoxin were purchased from Sigma (Vienna, Austria). HS-142-1 was a kind gift from Kyowo Hakko Kogyo (Japan) and indomethacin (Na-trihydrate) from Merck (Rahway, NJ, USA). All other chemicals were of standard grade.

2.8 Data analysis and calculations
Group data are presented as arithmetic mean values±S.E.M. Measurements of hemodynamic parameters and cGMP levels were subjected to a two-way analysis of variance (ANOVA) for repeated measurements to account for different CNP concentrations and factors (vehicle and inhibitors). When a significant overall effect was detected, the Scheffe test was performed to compare single mean values. The statistical treatment was always applied to the original data (mmHg perfusion pressure; nmol cGMP/l effluent). Conversion to percentage values was then done to facilitate comparison between treatments. A probability of <5% was considered significant. P values <0.01 are not indicated separately.


   3 Results
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
4 Discussion
 5 Conclusion
 References
 
3.1 Functional performance of hearts
The functional parameters of hearts at baseline are shown in Table 1. Coronary perfusion pressure was 132±1 mmHg, left ventricular developed pressure (LVDevP) was 85±5 mmHg, left ventricular end-diastolic pressure was 5±1 mmHg and heart rate was 297±6 beats/min (n=6). Test drugs had no effect on cardiac function, except that LVDevP was reduced by L-NNA (–24%), presumably due to the suppression of the positive inotropic effect of endogenous NO [21].

3.2 Response to CNP and vascular inhibitory effect of L-NNA
The three concentrations of CNP (0.1, 0.3 and 3 µmol/l) chosen for this study reduced perfusion pressure to 102±3, 76±1 and 71±1 mmHg (–24%, –43% and –48% of baseline pressure, respectively (controls; P<0.05 vs. baseline; n=6). In the presence of the NO synthase inhibitor L-NNA, the corresponding reduction in perfusion pressure was less, namely –14±1%, –30±3% and –37±2% (P<0.05 vs. corresponding control) (Fig. 1).


Figure 1
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  		Fig. 1 Coronary relaxation induced by CNP in absence and presence of the NO synthase inhibitor (0.2 mmol/l L-NNA). The relaxant effect of CNP is expressed as percent reduction of perfusion pressure from the respective baseline value listed in Table 1. Values are mean±S.E.M., n=6 hearts; *, P<0.05 vs. control at the respective CNP concentration.

 
3.3 Involvement of K+ channels in CNP relaxation
Blockade of K+ channels with glibenclamide or iberiotoxin modified the relaxant effect of CNP. In the presence of glibenclamide, CNP (0.1, 0.3 and 3 µmol/l) reduced perfusion pressure to 112±1, 102±3 and 92±2 mmHg (–17%, –24% and –32% of baseline, respectively) (Fig. 2). For iberiotoxin the corresponding perfusion pressure values were 114±1, 104±2 and 93±1 mmHg (–15%, –23% and –30% of baseline, respectively) (n=6; P<0.05 vs. corresponding control in both cases). The combination of both blockers reduced the relaxant effect of CNP even further (–9, –17 and –23% of baseline, respectively). These values were significantly different from glibenclamide alone as well as iberiotoxin alone at 0.3 and 3 µmol/l CNP. Other functional parameters were not affected (Table 1).


Figure 2
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  		Fig. 2 Coronary relaxation induced by CNP in absence and presence of glibenclamide (1 µmol/l) or iberiotoxin (30 nmol/l) that block ATP-dependent and Ca2+-dependent K+ channels, respectively. The combination of both blockers was also tested. Values are mean±S.E.M., n=6 hearts; *, P<0.05 vs. control at the respective CNP concentration; {dagger}, P<0.05 vs. glibenclamide or iberiotoxin above.

 
3.4 cGMP levels in coronary effluents
Basal release of cGMP was 0.62±0.04 nmol/l coronary effluent, and CNP increased release in concentration-dependent manner up to ~4-fold (n=3; P<0.05 vs. baseline). In the presence of L-NNA, CNP-induced cGMP formation was reduced by –26%, –49% and –52%, respectively at 0.1, 0.3 and 3 µmol/l CNP. Acetylcholine (10 nmol/l) increased cGMP in coronary effluent from 0.59±0.03 to 1.01±0.03 nmol/l (1.7-fold); in the additional presence of L-NNA the level was 0.39±0.08 nmol/l (–61%; n=3). Thus, L-NNA treatment similarly abolished the increase in cGMP efflux induced by CNP or acetylcholine (Fig. 3).


Figure 3
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  		Fig. 3 Stimulatory effect of CNP and acetylcholine (Ach) on cGMP release in coronary effluent and inhibitory effect of L-NNA. Hearts were perfused with CNP or Ach (10 nmol/l) in absence or presence of L-NNA (0.2 mmol/l), effluent samples were taken between 2 and 5 min after each dose of agonist and directly subjected to radioimmunoassay. Values are mean±S.E.M., n=3 hearts in each group. *, P<0.05 vs. control at respective CNP concentration.

 
3.5 Effect of NP receptor blockade and source of cGMP
To put the endothelial component of the CNP effect in perspective, and to determine the source of cGMP appearing in the effluent, we used the non-peptide NP receptor antagonist HS-142-1 which blocks both smooth muscle and endothelial NP receptors [9]. The perfusion pressure lowering effect of CNP was more strongly reduced by HS-142-1 than in the presence of L-NNA, i.e. when only the endothelial component was blocked (compare Fig. 4A and Fig. 1). Likewise, cGMP efflux was significantly less in the presence of the NP receptor blocker (Fig. 4B) than in the presence of L-NNA (Fig. 3). These data support the conclusion that both endothelium-derived and smooth muscle-derived cGMP are involved in the CNP-induced relaxation, and that the source of the cGMP remaining after L-NNA is of particulate guanylyl cyclase origin (Fig. 4).


Figure 4
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  		Fig. 4 Inhibitory effect of HS-142-1 on coronary relaxation (A) and cGMP generation (B) induced by CNP. Hearts were exposed to the receptor blocker (50 µg/ml; ~12 µmol/l final concentration) for 10 min and CNP applied as above. Hearts were pre-treated with IBMX (1 mmol/l) to inhibit cGMP degradation. Values are mean±S.E.M., n=6 hearts (A) and 3 determinations (B), respectively.*, P<0.05 vs. control at respective CNP concentration.

 
3.6 Organ bath experiments with rat aorta
In view of previous evidence against the involvement of the endothelium in natriuretic peptide-induced relaxation of aortic tissue, rings of rat aorta with preserved endothelium were prepared and the effect of CNP was tested in absence and presence of L-NNA (n=12 rings) (Fig. 5). Aortic rings were preconstricted with endothelin-1 (100 nmol/l), giving 5.2±0.3 g of tone. Contrary to its effect in the coronary vasculature, L-NNA had no effect on CNP-mediated relaxation (48±2% and 49±3% of preconstricted tone, respectively) or on the endothelium-independent relaxation induced by nitroprusside (62±1 and 66±1%, respectively) (P>0.05 in both cases). However, the endothelial NO–cGMP mechanism was intact in these aortas as evident from the relaxation induced by 100 nmol/l acetylcholine (control, 15±2% of preconstricted tone; in presence of L-NNA 5±2%) or 1 µmol/l of the calcium ionophor A 23187 (control, 34±5% of preconstricted tone; in presence of L-NNA 15±3% (n=11 rings; P<0.05 in both cases).


Figure 5
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  		Fig. 5 Lack of effect of L-NNA (0.2 mmol/l) in CNP-induced relaxation of rat aorta. Aortic rings were prepared, preconstricted with endothelin-1 (100 nmol/l) to 5.2±0.3 g (0% relaxation) and increasing concentrations of CNP were tested. For comparison, a maximally active concentration of nitroprusside (SNP, 100 µmol/l) was tested at the end of the experiment (columns). L-NNA had no significant effect on EC50 or maximum effect values. Data points represent mean±S.E.M. of twelve rings derived from three animals.

 

   4 Discussion
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
5 Conclusion
 References
 
The present in vitro study demonstrates that C-type natriuretic peptide relaxes the coronary microvasculature of the rat partly through activation of the NO–cGMP pathway, whereas this system plays no role in the relaxation of rat aorta. This is the first report demonstrating a role for the coronary endothelium in the vascular relaxant effect of C-type natriuretic peptide in hearts.

Previous authors studying the vasorelaxant effects of natriuretic peptides have generally concluded that these agonists do not require the presence of an intact endothelium for their vascular action [22–24]. Consistent with its systemic hypotensive effect, CNP has been shown to relax strips obtained from the aorta and saphenous arteries and veins. Removal of the endothelium either had no effect (in arteries) or potentiated the vasodilator response (in veins) [25]. We observed similar results in rat aortic rings, where inhibition of NO production with L-NNA did not diminish CNP-induced relaxation. In marked contrast to aorta, a conduit vessel, we consistently observed a smaller relaxation of the intact coronary vasculature after blockade of NO synthase with L-NNA, i.e. the reduction in perfusion pressure was less when NO generation was attenuated. The inhibitory effect of NO synthase blockade we observed is similar to that noted in a recent preliminary report in the human forearm which concluded that endothelium-derived NO plays a role in the vasodilatory effect of ANP [26]. However, while in this latter study ANP-induced changes in vascular blood flow probably played a role, such effects can be excluded in our study because the same perfusate flow-rate (9 ml/min) was used both in absence and presence of L-NNA. Because any arteriolar dilation, as evident from a reduced perfusion pressure, would reduce rather than increase shear forces, the NO–cGMP-mediated dilatory effect of CNP would be underestimated, not overestimated in our study. The postulate of an endothelium-dependent action of CNP may seem to be at odds with the belief of a predominantly smooth muscle localization of NPR-B receptors that are activated by CNP [8]. However, the receptor distribution of microvascular endothelial cells is not known, and the action of CNP can be independent of NPR-B receptors [27].

The involvement of the NO–cGMP system in CNP-induced coronary relaxation also is strongly supported by our cGMP measurements in coronary effluents. To ascertain full and precise recovery of the nucleotide, its degradation by phosphodiesterases was inhibited with IBMX during the course of the CNP stimulation. Significantly, CNP-stimulated cGMP efflux was reduced up to 50% in the presence of L-NNA (0.2 mmol/l), compared to a reduction of ~70% caused by HS-142-1 (50 µg/ml) (Fig. 4B). At the concentrations used, the two drugs are maximally effective in inhibiting the constitutive NO synthase isoforms [28] and in blocking NP receptors in smooth muscle and endothelial cells, respectively [9,19]. Consequently, the cGMP measured in the coronary effluent upon CNP infusion was partly derived from stimulation of soluble guanylyl cyclase (L-NNA-inhibitable portion) and partly from stimulation of the particulate enzyme (bulk of remaining portion). cGMP extrusion has been reported from various cells including platelets, endothelial cells and myocytes [29], is considered to be a regulated, energy-dependent process and to reflect the balance between cyclic nucleotide generation and degradation. In agreement with this view, we found no cGMP efflux from hearts in the absence of IBMX, indicating that the blocker gained access to the cells, and a considerably reduced efflux in the presence of HS-142-1 (Fig. 4B). Finally, ODQ, a selective inhibitor of soluble guanylyl cyclase [30], also inhibited cGMP efflux from isolated perfused hearts [31].

We also tested whether K+ channels might be involved in the relaxant effect of CNP in the coronary microvasculature. Previously, CNP was shown to hyperpolarize arterial vascular smooth muscle of isolated conduit porcine coronary artery [32], and ANP-mediated relaxation of rat coronary resistance vessels was substantially inhibited by tetraethyl ammonium ion, presumably by blocking Ca2+-activated K+ channels [16]. In addition, some dilation of coronary vessels could be mediated by ATP-dependent K+ (K+ATP) channels. To assess the involvement of either K+ channel in the present study, we have used glibenclamide, a selective antagonist at K+ATP channels [33] not previously tested in natriuretic peptide-induced coronary relaxation, and iberiotoxin, a selective blocker of Ca2+-activated K+ channels. We consistently found a substantial attenuation of relaxation in the presence of either blocker that was greater than that observed with L-NNA at the higher CNP concentrations (compare Figs. 1 and 2Go). Together, the K+ channel blockers were even slightly more effective, indicating a parallel cellular mechanism of action. Thus, the relaxation of CNP in the coronary microvasculature of the rat partly involves activation of the NO–cGMP pathway, followed by opening of smooth muscle cell K+ channels. The component of the CNP effect remaining after NO synthase blockade is not mediated by the endothelium. Presumably, the cGMP derived from stimulation (by CNP) of the particulate cyclase form, estimated as the HS-142-1-inhibitable minus the L-NNA-inhibitable cGMP, also acts via stimulation of K+ channels as suggested by the higher relaxation inhibitory potency of glibenclamide or iberiotoxin than that of L-NNA. This interpretation is in line with previous evidence that showed cGMP-modulation of Ca2+-activated K+ channels by ANP in coronary artery smooth muscle cells of the dog [34].

The present findings appear to be of considerable clinical relevance [35]. Many studies have shown that the vascular endothelium functions abnormally in experimental and human heart failure. The vasodilatory potency of atrial natriuretic peptides was blunted in the limb vascular bed and levels of cGMP were lower in patients with congestive heart failure compared to levels in healthy controls [36,37]. Furthermore, in conscious rats injection of a NO synthase inhibitor before administering ANP suppressed the hypotensive effect of the peptide, suggesting that the vascular endothelium and NO production are involved in the vasodilator effect of ANP as well [31,38]. Together, these latter and the present findings strongly support the view of natriuretic peptides as partially endothelium-dependent endogenous regulators of coronary and peripheral resistance.


   5 Conclusion
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
References
 
The simplest interpretation of the present results is that exogenous CNP relaxes the isolated perfused coronary vasculature, but not the aorta of the rat, in an endothelium-dependent manner. The investigation also provides evidence that the relaxant action of this locally produced peptide is in part transduced via endothelial receptors, followed by activation of endothelial NO synthase and smooth muscle soluble guanylyl cyclase. Our data suggest an interaction between endothelial natriuretic peptide receptor activation and the coronary NO synthase–soluble guanylyl cyclase system in the rat coronary vasculature and further support a functional link between the soluble and particulate guanylyl cyclase systems [39]. Further studies are necessary to address various aspects of the mechanism of this interaction, including the precise role of endothelial calcium and cGMP in NO synthase activation following CNP binding to endothelial receptors.

Time for primary review 35 days.


   Acknowledgements
 
We are indebted to Dr. Satoshi Nakanishi, Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co., for supplying the NP receptor antagonist HS-142-1. Helpful technical assistance of Mrs. B. Jelinek-Fink and Mrs. B. Oberer is also acknowledged. This work was supported by the Austrian Research Fund (Fonds zur Förderung der wissenschaftichen Forschung in Österreich), projects 12934 and 13013.


   References
Top
 Abstract
 1 Introduction
 2 Methods
 3 Results
 4 Discussion
 5 Conclusion
 References
 

  1. De Bold A.J., Kuroski-De Bold M.L., Boer P.H., et al. A decade of atrial natriuretic factor research. Can J Physiol Pharmacol (1991) 69:1480–1485.[Web of Science][Medline]
  2. Ruskoaho H. Atrial natriuretic peptide: synthesis, release and metabolism. Pharmacol Rev (1992) 44:479–602.[Web of Science][Medline]
  3. Melo L.G., Veress A.T., Ackermann U., et al. Chronic regulation of arterial blood pressure in ANP transgenic and knockout mice: role of cardiovascular sympathetic tone. Cardiovasc Res (1999) 43:437–444.[Abstract/Free Full Text]
  4. Stingo A.J., Clavell A.L., Heublein D.M., et al. Presence of C-type natriuretic peptide in cultured human endothelial cells and plasma. Am J Physiol (1992) 263:H1318–H1321.[Web of Science][Medline]
  5. Suga S.-I., Nakao K., Itoh H., et al. Endothelial production of C-type natriuretic peptide and its marked augmentation by transforming growth factor-β: possible existence of ‘vascular natriuretic peptide system’. J Clin Invest (1992) 90:1145–1149.[Web of Science][Medline]
  6. Clavell A.L., Stingo A.J., Wei C.-M., et al. C-type natriuretic peptide: a selective cardiovascular peptide. Am J Physiol (1993) 264:R290–R295.[Web of Science][Medline]
  7. Chinkers M., Garbers D.L., Chang M.-S., et al. A membrane form of guanylate cyclase is an atrial natriuretic peptide receptor. Nature (1989) 338:78–83.[CrossRef][Medline]
  8. Koller K.J., Low D.G., Bennett G.L., et al. Selective activation of the B natriuretic peptide receptor by C-type natriuretic peptide (CNP). Science (1991) 252:120–123.[Abstract/Free Full Text]
  9. Imura R., Sano T., Goto J., et al. Inhibition by HS-142-1, a novel nonpeptide atrial natriuretic peptide antagonist of microbial origin, of atrial natriuretic peptide-induced relaxation of isolated rabbit aorta through the blockade of guanylyl cyclase-linked receptors. Mol Pharmacol (1992) 42:982–990.[Abstract]
  10. Drewett J.G., Fendly B.M., Garbers D.L., et al. Natriuretic peptide receptor-B (guanylyl cylcase-B) mediates C-type natriuretic peptide relaxation of precontracted rat aorta. J Biol Chem (1995) 270:4668–4674.[Abstract/Free Full Text]
  11. Leitman D.C., Andresen J.W., Kuno T., et al. Identification of multiple binding sites for atrial natriuretic factor by affinity cross-linking in cultured endothelial cells. J Biol Chem (1986) 261:11650–11655.[Abstract/Free Full Text]
  12. Redmond E.M., Cahill P.A., Keenan A.K. Atrial natriuretic factor recognizes two receptor subtypes in endothelial cells cultured from bovine pulmonary artery. FEBS Lett (1990) 269:157–162.[CrossRef][Web of Science][Medline]
  13. Nazario B., Hu R.-M., Pedram A., et al. Atrial and brain natriuretic peptides stimulate the production and secretion of C-type natriuretic peptide from bovine aortic endothelial cells. J Clin Invest (1995) 95:1151–1157.[Web of Science][Medline]
  14. Amin J., Carretero O.A., Ito S. Mechanisms of action of atrial natriuretic factor and C-type natriuretic peptide. Hypertension (1996) 27(Part 2):684–687.[Abstract/Free Full Text]
  15. Stoclet J.-C., Andriantsitohaina R., Kleschyov A., et al. Nitric oxide and cGMP in regulation of arterial tone. Trends Cardiovasc Med (1998) 8:14–19.[CrossRef][Web of Science]
  16. Price J.M., Hellermann A. Inhibition of cGMP mediated relaxation in small rat coronary arteries by block of Ca2+ activated K+ channels. Life Sci (1997) 61:1185–1192.[CrossRef][Web of Science][Medline]
  17. Brunner F., Leonhard B., Kukovetz W.R., et al. Role of endothelin, nitric oxide and L-arginine release in ischaemia–reperfusion injury of rat heart. Cardiovasc Res (1997) 36:60–66.[Abstract/Free Full Text]
  18. Haynes W.G., Ferro C.J., O'Kane K.P.J., et al. Systemic endothelin receptor blockade decreases peripheral vascular resistance and blood pressure in humans. Circulation (1996) 93:1860–1870.[Abstract/Free Full Text]
  19. Matsuda Y., Morishita Y. HS-142-1: a novel nonpeptide atrial natriuretic peptide antagonist of microbial origin. Cardiovasc Drug Rev (1993) 11:45–59.[CrossRef][Web of Science]
  20. Kühberger E., Groschner K., Kukovetz W.R., et al. The role of myoendothelial cell contact in non-nitric oxide-, non-prostanoid-mediated endothelium-dependent relaxation of porcine coronary artery. Br J Pharmacol (1994) 113:1289–1294.[Web of Science][Medline]
  21. Kelly R.A., Han X. Nitrovasodilators have (small) direct effects on cardiac contractility: is this important? Circulation (1997) 96:2493–2495.[Web of Science][Medline]
  22. Scivoletto R., Carvalho M.H. Cardionatrin causes vasodilation in vitro which is not dependent on the presence of endothelial cells. Eur J Pharmacol (1984) 101:143–145.[CrossRef][Web of Science][Medline]
  23. Rapoport R.M., Waldman S.A., Schwartz K., et al. Effects of atrial natriuretic factor, sodium nitroprusside and acetylcholine on cyclic GMP levels and relaxation in rat aorta. Eur J Pharmacol (1985) 115:219–229.[CrossRef][Web of Science][Medline]
  24. Murohara T., Kugiyama K., Yasue H. Interactions of nitrovasodilators, atrial natriuretic peptide and endothelium-derived nitric oxide. J Vasc Res (1996) 33:78–85.[Web of Science][Medline]
  25. Wei C.-M., Aarhus L.L., Miller V.M., et al. Action of C-type natriuretic peptide in isolated canine arteries and veins. Am J Physiol (1993) 264:H71–H73.[Web of Science][Medline]
  26. Sugamori T., Sakane T., Ishibashi Y., et al. Atrial natriuretic peptide has nitric oxide-mediated vasodilatory effect? Circulation (1999) 100:I–438. Abstract.
  27. Trachte G.J., Drewett J.G. C-type natriuretic peptide neuromodulates independently of guanylyl cyclase activation. Hypertension (1994) 23:38–43.[Abstract/Free Full Text]
  28. Mayer B., Andrew P. Nitric oxide synthases: catalytic function and progress towards selective inhibition. Naunyn-Schmiedeberg's Arch Pharmacol (1998) 358:127–133.[CrossRef][Web of Science][Medline]
  29. Kitakaze M., Node K., Komamura K., et al. Evidence for nitric oxide generation in the cardiomyocytes: its augmentation by hypoxia. J Mol Cell Cardiol (1995) 27:2149–2154.[CrossRef][Web of Science][Medline]
  30. Brunner F., Schmidt K., Nielsen E.B., et al. Novel guanylyl cyclase inhibitor potently inhibits cyclic GMP accumulation in endothelial cells and relaxation of bovine pulmonary artery. J Pharmacol Exp Ther (1996) 277:48–53.[Abstract/Free Full Text]
  31. Brunner F., Wölkart G. Endothelial NO/cGMP system contributes to natriuretic peptide-mediated coronary and peripheral vasodilation. Microvasc Res (2001) 61:102–110.[CrossRef][Web of Science][Medline]
  32. Barton M., Bény J.-L., d'Uscio L.V., et al. Endothelium-independent relaxation and hyperpolarization to C-type natriuretic peptide in porcine coronary arteries. J Cardiovasc Pharmacol (1998) 31:377–383.[CrossRef][Web of Science][Medline]
  33. Challinor-Rogers J.L., McPherson G.A. Potassium channel openers and other regulators of KATP channels. Clin Exp Pharmacol Physiol (1994) 21:583–597.[Web of Science][Medline]
  34. Taniguchi J., Furukawa K.-I., Shigekawa M. Maxi K+ channels are stimulated by cyclic guanosine monophosphate-dependent protein kinase in canine coronary artery smooth muscle cells. Eur J Physiol (1993) 423:167–172.[CrossRef][Web of Science][Medline]
  35. Lisy O., Burnett J.C. Jr. Potential future therapies: natriuretic peptides. Coron Artery Dis (1999) 10:389–394.[Web of Science][Medline]
  36. Nakamura M., Arakawa N., Yoshida H., et al. Vasodilatory effects of C-type natriuretic peptide on forearm resistance vessels are distinct from those of atrial natriuretic peptide in chronic heart failure. Circulation (1994) 90:1210–1214.[Abstract/Free Full Text]
  37. Nakamura M. Peripheral vascular remodeling in chronic heart failure: clinical relevance and new conceptualization of its mechanisms. J Cardiac Fail (1999) 5:127–138.[CrossRef][Web of Science][Medline]
  38. Angeles Costa M., Bosc L.V.G., Majowicz M.P., et al. Atrial natriuretic peptide modifies arterial blood pressure through nitric oxide pathway in rats. Hypertension (2000) 35:1119–1123.[Abstract/Free Full Text]
  39. Marumo T., Nakaki T., Hishikawa K., et al. Natriuretic peptide-augmented induction of nitric oxide synthase through cyclic guanosine 3',5'-monophosphate elevation in vascular smooth muscle cells. Endocrinology (1995) 136:2135–2142.[Abstract]

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