[Vasodilator effects of bradykinin on the resistive circulation of the forearm of coronary patients].

This study was undertaken to determine the vascular effects of bradykinin and its modes of action on the resistive circulation of the forearms of coronary patients and healthy volunteers. Two groups were studied: Group I comprising 8 coronary patients with normal left ventricular function and Group II with 8 healthy volunteers. The method of measurement of forearm blood flow was occlusive venous plethysmography with a mercury strain gauge. The vasodilatory response of the two groups to local arterial perfusion of acetylcholine (40 and 80 micrograms/min), bradykinin (10, 30, 100 pmoles/min), then the association of L-Ng-monomethyl-L-arginine (L-NMMA) at 8 microG/min, an inhibitor of the synthesis of nitric oxide, with acetylcholine and bradykinin. Five subjects of the control group received oral aspirin (250 mg/day) for one week before the study. Acetylcholine and bradykinin increased forearm flow in a dose-dependent manner but the increase was significantly less in coronary patients than in the healthy volunteers (p < 0.05). The L-NMMA inhibited the vasodilatory response to acetylcholine by about 40% in the two groups but had no significant effect on the vasodilatation induced by bradykinin. Aspirin had no effect on the vasodilatation induced by acetylcholine or bradykinin. These data show that the vasodilatory response to bradykinin is decreased in coronary patients and suggest that nitric oxide is not the second main messenger of bradykinin in the resistive circulation of the forearm.