The inhibitory effect of pioglitazone on agonist-dependent vascular contractility

Abstract

The present study was undertaken to determine whether pioglitazone treatment influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Pioglitazone decreased Rho-kinase activating agonist-induced contraction but not phorbol ester-induced contraction suggesting the least involvement of Ca2+-independent thin filament regulation of contractility. Furthermore, pioglitazone decreased thromboxane A(2) mimetic-induced phosphorylation of MYPT1 at Thr855, the newly-highlighted site, instead of Thr696. In conclusion, this study provides the evidence and possible related mechanism concerning the vasorelaxing effect of pioglitazone as an antihypertensive on the agonist-induced contraction in rat aortic rings regardless of endothelial function.