© 1997 by European Society of Cardiology
Copyright © 1997, European Society of Cardiology
Endothelial dysfunction of conduit arteries in insulin-dependent diabetes mellitus without microalbuminuria
Department of Clinical Therapeutics, Alexandra University Hospital, Athens, Greece
* Corresponding author. 86 Alkionis Str., P. Faliron 17562, Athens, Greece. Tel. +30 1 9830088; Fax +30 1 7219445.
Received 9 October 1996; accepted 13 December 1996
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Abstract |
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 Top Abstract 1 Introduction2 Methods3 Results4 DiscussionReferences |
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Objective: Previous studies have shown that endothelial dysfunction, an early sign of atherosclerosis, occurs in animal models of diabetes mellitus and in resistance vessels of patients with insulin-dependent diabetes. In the present study we examined whether young patients with insulin-dependent diabetes without microalbuminuria present abnormal endothelial function of large peripheral arteries. Methods: Twenty-six patients with insulin-dependent diabetes without microalbuminuria were compared with 26 normal controls and 5 patients with insulin-dependent diabetes with microalbuminuria. Brachial artery diameter was measured at rest, during reactive hyperaemic flow (endothelium-dependent dilatation) and after sublingual isosorbide dinitrate (endothelium-independent dilatation). Results: Baseline artery diameter and flow as well as the degree of reactive hyperaemia were similar in all groups compared to controls. Flow-mediated dilatation was lower in patients with diabetes without microalbuminuria (5.8±7 vs 11±7%, P=0.01) as well as in patients with diabetes without microalbuminuria (0.75±2.5 vs 11±7%, P=0.003); nitrate-induced dilatation was normal in patients without microalbuminuria and attenuated in patients with microalbuminuria. In the group of diabetes patients without microalbuminuria, those with disease duration >10 years and HbA1c >6% had the worse endothelial function. Conclusions: Our results demonstrate that endothelial dysfunction of conduit arteries can be detected in patients with insulin-dependent diabetes mellitus without microalbuminuria, probably contributing to the high prevalence of atherosclerosis in these patients.
KEYWORDS Diabetes; Endothelium; Human
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1 Introduction |
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TopAbstract1 Introduction2 Methods3 Results4 DiscussionReferences |
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Cardiovascular disease is a major cause of excess mortality and morbidity in patients with insulin-dependent diabetes mellitus; atherosclerosis in these patients is usually diffused with early onset. Normal vascular endothelium contributes to the control of vessel wall homeostasis; there is accumulating evidence that impairment of endothelial function is an important feature of vascular disease not only in subjects with established atherosclerosis but also in subjects with risk factors for vascular disease before anatomic evidence of atherosclerosis [1–3]. There is now substantial evidence that endothelial dysfunction occurs in animal models of diabetes mellitus [4, 5]; endothelial dysfunction also appears to be present in forearm resistance vessels of patients with insulin-dependent diabetes [6]. Some investigators included in their studies patients with microalbuminuria which appears to be a marker of widespread vascular damage [6, 7].
The objective of the present study was to determine whether young patients with insulin-dependent diabetes mellitus without microalbuminuria present abnormal endothelial function of large peripheral arteries. Furthermore, we sought to determine whether a possible vascular dysfunction is confined to endothelium only, or whether it reflects an intrinsic impairment of the capacity of the smooth muscle cell to relax.
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2 Methods |
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TopAbstract1 Introduction2 Methods3 Results4 DiscussionReferences |
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2.1 Patient population
Twenty-six patients with insulin-dependent diabetes mellitus participated in the study; 9 were men and 17 women with a mean age of 32±8 years (range 16–46 years); duration of diabetes was 12.9±8 years (range 1–24 years). No patient had evidence of atherosclerosis as judged by absence of angina, claudication and cerebrovascular ischaemia; all patients had a normal electrocardiogram. No patient had microalbuminuria (albumin excretion rate <20 µg/min), systemic hypertension or cholesterol >240 mg/dl; 8 patients were chronic smokers. No patient had evidence of hepatic or renal dysfunction. Mean cholesterol level was 194±25 mg/dl (range 140–240 mg/dl) and mean triglycerides level was 89±34 mg/dl (range 49–174 mg/dl); body mass index was 25.5±3.6 kg/m2 (range 20–33 kg/m2). Mean HbA1c during the last 6 months before the study (average of at least 2 measurements) was 6.5±1.5% (range 5–11%); 11 patients had HbA1c<6% and 15 patients HbA1c >6%. Mean daily dose of insulin was 46±16 IU (range 20–80 IU). Patients were taking no medications other than insulin. Results were compared with 26 normal subjects matched for sex; age was similar in the two groups (32±8 vs 34±9 years, n.s.); 10 normal subjects were smokers and no control subject had hypertension or cholesterol >240 mg/dl. A third group comprised of 5 patients with insulin-dependent diabetes mellitus and microalbuminuria. Age, body mass index, blood pressure, smoking habits, daily insulin dose and HbA1c were comparable in the two diabetic groups, while disease duration tended to be longer in patients with microalbuminuria, but the difference did not reach statistical significance (20±8.5 vs 12.9±8.4 years, P=0.09). Characteristics of the patients and control subjects are shown in Table 1. Informed consent was obtained from all participants in the study. The investigation conforms with the principles outlined in the Declaration of Helsinki.
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2.2 Measurements
Each subject was studied in the morning having abstained from alcohol, caffeine and tobacco as well as food for 8 h before the study. High-resolution echo-Doppler ultrasound (Acuson 128 XP, Mountain View, CA) with a 7.0 MHz transducer was used to measure flow velocity and diameter of the right brachial artery. In all studies scans were taken at rest, during reactive hyperaemia (an endothelium-dependent stimulus to vasodilatation), again at rest and after sublingual isosorbide dinitrate (an endothelium-independent vasodilator). The subject rested quietly for 10 min before the scan; when a satisfactory position was found, the skin was marked; a resting scan was recorded and arterial flow velocity was measured using a pulsed Doppler signal at 60° angle in the centre of the artery. Blood flow through the brachial artery was altered with an occluding cuff placed on the forearm approximately 8 cm distal to the site of brachial artery measurement [1]. By inflating the cuff to 250–300 mmHg distal circulatory arrest was obtained and flow was reduced through the brachial artery measured proximal to the cuff. By deflating the cuff after 5 min of inflation, flow through the brachial artery was increased (reactive hyperaemia). The brachial artery was scanned continuously 30 s before and 90 s after cuff deflation. Ten minutes later a second rest scan was recorded. Isosorbide dinitrate (5 mg) was then administered sublingually and the artery was scanned 5 min later.
Artery diameter was measured by consensus of two observers (J.L., C.P.) unaware of the stage of experiment. Measurements were made at end-diastole (peak of R-wave of ECG); 5 cardiac cycles were analyzed and measurements were averaged; volume flow was calculated by multiplying the time-averaged velocity of the Doppler flow signal by the heart rate and the vessel cross-sectional area (
r2) [1]. Flow-mediated dilatation was calculated as the percent increase in arterial diameter during hyperaemia compared to the corresponding resting value. Nitrate-induced dilatation was also calculated similarly. Reactive hyperaemia was calculated as the maximum flow during the first 15 s after cuff deflation divided by the corresponding rest flow [1].
2.3 Statistical analysis
Descriptive data are expressed as a mean±s.d. Student's t-test was used to analyze the difference between the means in each group. Linear regression analysis was used to assess the relationship between selected variables. Statistical significance was taken as P<0.05.
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3 Results |
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TopAbstract1 Introduction2 Methods3 Results4 DiscussionReferences |
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Baseline brachial artery diameter was comparable in patients with microalbuminuria (3.3±0.3 mm), patients without microalbuminuria (3.4±0.5 mm), and control subjects (3.5±0.5 mm, n.s.). Flow at rest and the degree of reactive hyperaemia were similar in patients and control subjects (Table 2).
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Flow-mediated dilatation was significantly lower in patients with microalbuminuria (0.75±2.5%, P=0.003) and without microalbuminuria (5.8±7%, P=0.01) compared to normal control subjects (11±7%). Nitrate-induced dilatation was normal in patients without microalbuminuria and attenuated in patients with microalbuminuria (15±2.9 vs 24±9%, P=0.03). These data suggest abnormal endothelial function in diabetic patients with or without microalbuminuria and smooth muscle dysfunction in patients with microalbuminuria (Table 2). Linear regression analysis did not reveal any statistically significant correlation between the vasodilatory response to hyperaemic flow and HbA1c, disease duration, age and daily dose of insulin.
To better characterize the possible influence of metabolic control on endothelial function, we analyzed the data in the group of patients with a mean HbA1c during the last 6 months higher or lower than 6%. Patients with good metabolic control (HbA1c >6%) tended to have a higher flow-mediated dilatation (7.5±6.8 vs 4.6±7.2%), but the difference did not achieve statistical significance (ns). By comparing the two groups of patients separately to the control subjects, only patients with HbA1c >6% presented a significantly lower endothelium-dependent vasodilatation (P=0.008) (Fig. 1). We also analyzed data on the basis of a disease duration higher or lower than 10 years. Patients with long disease duration tended to have a worse flow-mediated dilatation (5.0±8.3 vs 7.9±6.7%) without statistically significant differences (n.s.); when comparing the data of each group with the control subjects, only patients with long disease duration showed a significant difference (P=0.03) (Fig. 2).
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4 Discussion |
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TopAbstract1 Introduction2 Methods3 Results4 DiscussionReferences |
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In the present study we examined vascular endothelial and smooth muscle function in the large vessels of insulin-dependent diabetic patients using a simple non-invasive method which enabled accurate and reproducible assessment of the vascular responses to flow increase and nitrates [8]. In animals, flow-dependent dilatation is endothelium-dependent and mediated by nitric oxide [9, 10]; the same mechanism is essential for flow-mediated dilatation of large human arteries [11]. Hence, this test can be used as an estimate of the capacity of human endothelial cells to release nitric oxide in response to a physiological stimulus as well as an estimate of endothelial dysfunction in diseased states. To distinguish endothelial from intrinsic smooth muscle dysfunction, we used isosorbide dinitrate, an endothelium-independent vasodilator; nitrates cause smooth muscle to relax, acting directly by increasing cyclic GMP levels of smooth muscle cells [12]. We preferred to use this non-invasive and accurate method to test endothelial function of conduit arteries, instead of using intra-arterial infusion of acetylcholine which is an invasive method and in the forearm is usually used in conjunction with venous occlusion plethysmography to assess endothelial function of small resistance vessels.
The results of the present study in brachial artery clearly indicate the presence of endothelial dysfunction in insulin-dependent diabetes mellitus even in the absence of microalbuminuria. The most striking endothelial dysfunction was observed in patients with microalbuminuria, and in patients without microalbuminuria but with long disease duration and poor metabolic control. Zenere et al. [13]has also reported a reduced vasodilatation capacity using the same method in femoral artery; however, we should note that femoral artery diameter in adults is greater than 7.0 mm; for arteries of more than 6.0 mm in diameter flow-mediated dilatation is small and data from studies in adult femoral arteries should be interpreted with caution [8]. Previous studies in diabetic subjects have focused on endothelial function of small resistance vessels; most of these studies reported that endothelium-dependent vasodilatation is abnormal in forearm resistance vessels [6, 7, 14], although in two reports [15, 16]a deficit in endothelium-dependent vasodilatation of resistance vessels was not observed.
The response to nitrates was normal in patients without microalbuminuria and attenuated in diabetics with microalbuminuria although not to the same degree as the impairment of endothelium-dependent vasodilatation. This response indicates an abnormality of smooth muscle cells in patients with diabetes and microalbuminuria. It is known that microalbuminuria in diabetic patients reflects widespread vascular damage [17]and our observation of an impairment of the capacity of smooth muscle cells to relax in addition to endothelial dysfunction is in accord with this previous knowledge.
Various mechanisms have been proposed to explain endothelial dysfunction in diabetes. Reduced synthesis or accelerated inactivation of nitric oxide and excessive release of vasoconstrictor substances like thromboxane A2 and endothelin [18, 19]are among the proposed mechanisms. High levels of oxygen-derived free radicals or the accumulation of advanced glycosylation end-products may participate in the pathogenesis of endothelial dysfunction in these patients [20].
There is ample evidence that impairment of endothelium-dependent vasodilatation is an early phenomenon of atherogenesis and it is present in humans before the anatomic evidence of atherosclerosis [1–3]. Abnormal endothelial function results in abnormal reactions between the vessel wall and platelets, facilitates the adhesion of monocytes to the endothelial surface and enhances the proliferation of vascular smooth muscle cells [21–23], contributing to the genesis of atherosclerosis. Apparently the observed endothelial dysfunction in our patients reflects an early atherosclerotic process of large vessels.
In conclusion, the results of this study indicate that endothelium-dependent dilatation is impaired in the systemic arteries of young adults with insulin-dependent diabetes, even in the absence of microalbuminuria. Endothelial dysfunction is striking in patients with poor metabolic control, longer duration of diabetes and microalbuminuria and may represent early large vessel disease. Strategies to reduce or retard endothelial dysfunction in these patients may lead to decreased cardiovascular morbidity and mortality.
Time for primary review 26 days.
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References |
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TopAbstract1 Introduction2 Methods3 Results4 DiscussionReferences |
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- Celermajer DS, Sorensen KE, Georgakopoulos D, et al. Cigarette smoking is associated with dose-related and potentially reversible impairment of endothelium-dependent dilatation in healthy young adults. Circulation 1993;88(part 2):2149–2155.
- Antony I, Lerebours G, Nitenber A. Loss of flow-dependent coronary artery dilatation in patients with hypertension. Circulation 1995;91:1624–1628.
- Sorensen KE, Celermajer DS, Georgakopoulos D, Hatcher G, Betteridge DJ, Deanfield JE. Impairment of endothelium-dependent dilatation is an early event and is related to the lipoprotein (a) level. J Clin Invest 1994;93:50–55.
- Durante W, Sen AK, Sunahara FA. Impairment of endothelium-dependent relaxation in aortae from spontaneously diabetic rats. Br J Pharmacol 1988;94:463–468.
- Mayhan WG. Impairment of endothelium-dependent dilatation of cerebral arterioles during diabetes mellitus. Am J Physiol 1989;256:H621–H625.
- Johnstone MT, Creager SJ, Scales KM, Cuso JA, Lee BK, Creager MA. Impaired endothelium-dependent vasodilatation in patients with insulin-dependent diabetes mellitus. Circulation 1993;88:2510–2516.
- Elliott TG, Cockroff JR, Groop PH, Viberti GC, Ritter JM. Inhibition of nitric oxide synthesis in forearm vasculature of insulin-dependent diabetic patients: blunted vasoconstriction in patients with microalbuminuria. Clin Sci 1993;85:687–693.
- Celermajer DS, Sorensen KE, Gooch VM, et al. Non-invasive detection of endothelium dysfunction in children and adults at risk of atherosclerosis. Lancet 1992;340:1111–1115.
- Rubanyi GM, Romero JC, Vanhoutte PJ. Flow-induced release of endothelium-derived relaxing factor. Am J Physiol 1986;250:H1145–H1149.
- Pohl U, Holtz J, Busse R, Bassenge E. Crucial role of the endothelium in the vasodilator response to increased flow in vivo. Hypertension 1986;8:37–44.
- Joannides R, Haefeli WE, Linder L, et al. Nitric oxide is responsible for flow-dependent dilatation of human peripheral conduit arteries in vivo. Circulation 1995;91:1314–1319.
- Katz SD, Biasucci L Sabba C, et al. Impaired endothelium-mediated vasodilatation in the peripheral vasculature of patients with congestive heart failure. J Am Coll Cardiol 1992;19:981–925.
- Zenere BM, Azcaro G, Saggiani F, Ross L, Muggeo M, Lechi A. Noninvasive detection of functional alterations of the arterial wall in IDDM patients with and without microalbuminuria. Diabetes Care 1995;18:975–982.
- Calver A, Collier J, Vallance P. Inhibition and stimulation of nitric oxide synthesis in the human forearm arterial bed of patients with insulin-dependent diabetes. J Clin Invest 1992;90:2548–2554.
- Halkin A, Benjamin N, Doktor HS, Todd SD, Viberti G, Ritter JM. Vascular responsiveness and cation exchange in insulin-dependent diabetes. Clin Sci 1991;81:223–232.
- Smits P, Kapma JA, Jacobs MC, Lutterman J, Thien T. Endothelium-dependent vascular relaxation in patients with type 1 diabetes. Diabetes 1993;42:148–153.
- Deckert L, Feldt-Rasmussen B, Borch-Johnsen K, Jensen L Kofoed-Enevoldsen A. Albuminuria reflects widespread vascular damage: the Steno hypothesis. Diabetologia 1989;32:219–226.
- Bucala R, Tracey KJ, Cerami A. Advanced glycosylation productions quench nitric oxide and mediate defective endothelium-dependent vasodilatation in experimental diabetes. J Clin Invest 1991;87:432–438.
- Kanno K, Kirata Y, Shichiri M, Marumo F. Plasma endothelin-1 levels in patients with diabetes mellitus with or without vascular complication. J Cardiovasc Pharmacol 1991;17(suppl 7):475–476.
- Pieper GM, Gross GJ. Oxygen free radicals abolish endothelium dependent relaxation in diabetic rat aorta. Am J Physiol 1988;255:H825–H833.
- Radomski MW, Palmer RMJ, Moncada S. An L-arginine/nitric oxide pathway present in human platelets regulates aggregation. Proc Natl Acad Sci USA 1990;87:S/93–S/97.
- Kubes P, Suzuki M, Granger DN. Nitric oxide: an endogenous modulator of leucocyte adhesion. Proc Natl Acad Sci USA 1991;88:4651–4656.
- Garg UC, Hassid A. Nitric oxide-generating vasodilators and 8-bromocyclic guanosine monophosphate inhibit mitogenesis and proliferation of cultured rat vascular smooth muscle cells. J Clin Invest 1989;83:1774–1777.
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