Response of Intracellular Ca²⁺ Transients in Cultured Vascular Smooth Muscle Cells to Angiotensin II, Vasopressin, Acetylcholine and Atrionatriuretic Peptide

Abstract

Modulation of intracellular Ca²⁺ concentration ([Ca²⁺]_i) is a signal for the contraction of vascular smooth muscle cells responding to vasoreactive substances. We prepared confluently cultured smooth muscle cells from rat aorta, loaded them with Ca²⁺ sensitive fluorescent dye, fura-2, and measured the [Ca²⁺]_i transient by microscopic spectrofluorometry. The [Ca²⁺]_i was distributed heterogeneously in cytosol. Angiotensin II (10nM) transiently doubled the [Ca²⁺]_i. It was also increased by arginine-vasopressin (10nM), even after stimulation by angiotensin II was saturated. In contrast, acetylcholine (10μM) or rat atrionatriuretic peptide (10nM) did not change the [Ca²⁺]_i in the same detecting field of the same cell, contradicting previous reports