Effect of calcium antagonists on endothelin-induced contraction of isolated human resistance arteries: differences related to site of origin.

Small resistance arteries were isolated from human subcutaneous fat and omentum and studied using a myograph. Endothelin-1 induced a concentration-dependent contraction in both type of arteries. In subcutaneous arteries preincubation with calcium antagonists partially inhibited responses to endothelin-1. The effectiveness of the calcium antagonists was nisoldipine > nimodipine > verapamil = flunarizine > diltiazem. In omental arteries nimodipine and diltiazem had no significant effect on endothelin-1-induced contraction and removal of extracellular calcium also had little effect on responses to endothelin-1. The role of influx of extracellular calcium through voltage operated calcium channels in endothelin-1-induced contraction appear to differ between subcutaneous and omental resistance arteries.