Effect of transdermal nitroglycerin on glucose-stimulated insulin release in healthy male volunteers

Background Morpholinosydnonimine, a nitric oxide (NO) donor, has been repor ted to inhibit insulin release in isolated pancreatic islets. We studied wh ether transdermal application of nitroglycerin, another NO donor widely use d for angina prophylaxis, influenced glucose-stimulated insulin release in healthy, young, male volunteers. Methods and results Oral glucose tolerance tests [(OGTT) 75 g glucose in 20 0 mL of water) were performed in the presence of placebo patches or nitrogl ycerin-releasing 'active' patches (approx. 0.4 mg hour(-1) nitroglycerin) i n the same patients with a 2-week intertest interval. Venous blood samples were taken before and 15, 30, 60, 90, 120 and 180 min after the glucose loa d and evaluated for plasma glucose level and immunoreactive insulin respons es (radioimmunoassay). Glucose-stimulated maximum increase in plasma insuli n immunoreactivity were 36.3 +/- 5 and 78.8 +/- 6.1 mU mL(-1) (P < 0.05) in the presence of active and placebo patches, respectively. Nevertheless, bo th fasting and postload blood glucose levels were the same at either patch. Active patches significantly decreased blood pressure with a marginal incr ease in heart rate. Conclusion We conclude that inhibition of glucose-stimulated insulin releas e by transdermal nitroglycerin without causing hyperglycaemia may serve as a novel component of the antianginal mechanism of action of nitrates.