Changes in blood glucose and plasma insulin levels induced by bradykinin in anaesthetized rats

1 The influence of bradykinin (BK) on blood glucose and plasma insulin leve ls was investigated in anaesthetized rats. 2 Blood glucose level was dose-dependently increased by intravenous infusio n of BK. This effect of BK was enhanced by captopril, an inhibitor of angio tensin-converting enzyme (ACE). Des-Arg(9)-bradykinin (DABK), a kinin B-1 r eceptor agonist, did not modify blood glucose levels while the effect of BK was inhibited by Hoe-140, a kinin B-2 receptor antagonist. The effect of B K was reduced by the NO-synthase inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME), and by the cyclo-oxygenase inhibitor, indomethacin. 3 The effect of BK was suppressed by the association of propranolol with ph entolamine or phenoxybenzamine. It was also reduced by hexamethonium, a gan glion-blocking drug. In adrenalectomized rats, the infusion of BK slightly decreased blood glucose levels. 4 The hyperglycaemic effect of adrenaline was suppressed by propranolol ass ociated with phentolamine or phenoxybenzamine, but it was not modified by L -NAME. 5 Infusion of BK did not modify plasma insulin levels. However, after phent olamine and propranolol, BK induced a transient 2 fold rise in plasma insul in levels. The release of insulin was dose-dependent and inhibited by Hoe-1 40. 6 We conclude that infusion of BK induces, via a stimulation of B-2 recepto rs, the release of NO and of prostanoids. The latter agents activate throug h a reflex pathway the release of catecholamines from the adrenal medulla. This release increases blood glucose levels and reduces plasma insulin leve ls. After adrenoceptor inhibition, BK induces a secretion of insulin, via t he stimulation of B-2 receptors.