Abstract
The inhibitory effect of 1, 9-dideoxyforskolin (DFK) on the contraction of rat aorta was compared with that of forskolin. DFK inhibited the contraction induced by high K+ more strongly than that induced by norepinephrine, whereas forskolin more strongly inhibited the norepinephrine-induced contraction. The inhibitory effect of DFK on high K+-induced contraction was antagonized by an increase in extracellular Ca2+ concentration. DFK inhibited the increase in cytosolic Ca2+ level and contraction in parallel whereas forskolin inhibited the contraction more strongly than the cytosolic Ca2+ level. These results suggest that DFK, but not forskolin, inhibits vascular smooth muscle contraction by a Ca2+ channel blocker-like action.
