Prostaglandin F 2α(PGF 2α)-induced contraction and calcium movement in longitudinal muscle of guinea-pig isolated stomach

Abstract

Calcium movement and contractile responses to high K + concentration and PGF 2α were investigated in guinea-pig stomach longitudinal muscle. High K + concentration(30 mM) and PGF 2α(10 −7M) produced similar contractions of guinea-pig stomach longitudinal muscle. The ‘Ca-antagonist’, verapamil (10 −5–10 −4M), prevented high K-induced contraction, but did not greatly reduce contractions to PGF 2α. 45Ca uptake was increased by high K(30 mM) or PGF 2α(10 −7M). These increases in 45Ca uptake were greatly reduced with 10 −4M verapamil. The results suggest that high K-induced contraction may depend on an increase in Ca influx. PGF 2α-induced contraction may depend on both an increase in Ca influx and on an intracellular release of Ca.