Further investigations on potassium-induced automaticity of isolated human renal artery

Experiments were designed to investigate generation of automaticity of isolated human renal arteries induced by administration of potassium in vitro. Helical strips of human renal arteries showed marked oscillations in the potassium-induced contractions which persisted for 2 hr. Indomethacin and aspirin dose-dependently inhibited these oscillations. Tranylcypromine and mepacrine also had an inhibitory action on the oscillations of the strips induced by potassium. In the strips which reached a steady state 2 hr after administration of potassium, phospholipase A2 and bradykinin produced marked oscillations. Our results indicate that human renal arteries can generate automaticity in the contractions induced by potassium, and that such automaticity may be related to the biosynthesis of prostaglandins.