Copyright © 2007, European Society of Cardiology
Celecoxib dilates guinea-pig coronaries and rat aortic rings and amplifies NO/cGMP signaling by PDE5 inhibition
aDepartments of Biochemistry and Pharmacology, ALTANA Pharma AG, D-78467 Konstanz, Germany
bDepartment of Pediatrics, Philipps-University, Baldingerstr, D-35041 Marburg, Germany
* Corresponding author. Tel.: +49 6421 2862650; fax: +49 6421 2868956. martin.komhoff{at}web.de
Objective Celecoxib carries a smaller cardiovascular risk for myocardial infarction and hypertension than other cyclooxygenase-2 (COX-2)-selective non-steroidal anti-inflammatory drugs NSAIDs ("coxibs") and may ameliorate endothelial dysfunction. We aimed to determine which mechanism possibly accounts for the beneficial effect by investigating its vascular action in different in vitro preparations in comparison with other coxibs and reference phosphodiesterase-5 (PDE5) inhibitors.
Methods To uncover potential effects on coronary flow, the effects of celecoxib in comparison with other NSAIDs and the PDE5 inhibitors, sildenafil and zaprinast, were investigated in guinea-pig Langendorff heart. This was supported by studies for vasorelaxation, interaction with the NO/cGMP pathway, and measurement of cyclic nucleotide amounts released from rat aortic rings, and inhibition of human PDE5 as well as PDE4 activity.
Results Bolus injections of sildenafil, celecoxib, and zaprinast (at 100 nmol) into the Langendorff heart increased coronary flow by approximately 100, 65, and 25%, respectively, while rofecoxib, lumiracoxib, parecoxib, and diclofenac, except valdecoxib (>100 nmol), failed to increase coronary flow up to 300 nmol. In rat aorta, sildenafil, celecoxib and zaprinast caused endothelium-dependent relaxation with –log[EC50]M values of 8.90, 6.66 and 5.56, respectively; their rank order of potency corresponds to their coronary dilatory effect. Celecoxib-induced relaxation of aorta was attenuated by the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10–4 M) and by the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-
]quinoxalin-1-one (ODQ, 10–5 M). In aortic rings, celecoxib (3x10–5 M) caused a fivefold increase in the cGMP level and potentiated that induced by sodium nitroprusside (5x10–7 M). Celecoxib and valdecoxib inhibited human PDE5A1 with an IC50 of 1.6x10–5 and 1x10–4 M, respectively, whereas other coxibs were without inhibitory effect.
Conclusion Celecoxib caused coronary vasodilatation in guinea-pig hearts and relaxation of rat aorta and had a potentiating effect on the NO/cGMP signaling pathway in rat aorta through specific blockade of PDE5. These unexpected findings clearly support the notion that celecoxib possesses an as yet undisclosed molecule-specific property that possibly compensates a decrease of prostacyclin-dependent cAMP generation by concomitantly increasing cGMP levels resulting from inhibition of PDE5.
KEYWORDS Coronary flow; Celecoxib; NSAID; PDE5; cGMP
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