Clofibrate and vascular smooth muscle: actions on rabbit aorta preparations

Clofibrate (Atromid-S) has been found to inhibit the contractility of isolated rabbit aortic muscle rings produced by exposure to either norepinephrine, histamine or angiotensin. The inhibitory effect of clofibrate is seen optimally in Krebs medium containing low, 5 X 10-5 M, calcium but is not found in medium containing 2.5 X 10-3 M calcium. In contrast, clofibrate does not inhibit contractions triggered by depolarizing concentrations of K+, in either low or normal Ca medium. Since only receptor-mediated contractions are inhibited, it is suggested that the actions of clofibrate in aorta influence an event common to receptor-linked contractions, possibly by interfering with the utilization of membrane-bound calcium.