PROPERTY OF POTASSIUM-INDUCED CONTRACTURE OF THE GUINEA-PIG TRACHEAL MUSCLE IN RELATION TO CALCIUM

Abstract

High K induced a sustained contracture in guinea-pig tracheal muscle, of which tonic tension level was dependent on the external K and the external Ca concentration. Ca-free-solution, DNP and malonate applied before the high K application completely inhibited the tension development with high K, whereas these agents partially inhibited the tension when applied during K contracture. Anoxia and glucose-free-solution had little or no effect on K contracture. No phasic contraction was observed under any of the present experimental conditions. The results indicate that the uptake of the extracellular Ca by energy-requiring process is essential for K contracture of tracheal muscle.