Abstract
TAKEUCHI, K., ABE, K., YASUJIMA, M., SATO, M., MAEYAMA, K., WATANABE, T., SATO, S., INABA, H. and YOSHINAGA, K. Phosphoinositide Hydrolysis and Calcium Mobilization Induced by Vasopressin and Angiotensin II in Cultured Vascular Smooth Muscle Cells. Tohoku J. Exp. Med., 1992, 166 (1), 107-122-The cellular action of vasoconstrictive hormones, angiotensin II (AII) and Arg8-vasopressin (AVP), on vascular smooth muscle (VSM) in cultured VSM cells from rat mesenteric artery was studied. Both AII and AVP specifically induce a transient increases in cytosolic free calcium independent of extracellular calcium or calcium channels activated by high potassium depolarization in VSM cells loaded with Fura-2. Vasoconstrictive hormones induce a dose-dependency with formation of inositolphosphates. Analysis using high pressure liquid chromatography has shown that AVP stimulates rapid and transient increases in inositol 1, 3, 4-trisphosphate, inositol 1, 4, 5-trisphosphate and inositol 1, 3, 4, 5-tetrakisphosphate within 1 minute. Moreover, a laser-excitation fluorescence system reveals high calcium concentration sites in subsarcolemmal region. These results indicate that, unlike voltage-dependent calcium influx across the cell membrane, AII and AVP induce receptor-mediated increases in cytosolic free calcium via phosphoinositide hydrolysis creating an intracellular messenger for calcium release from intracellular calcium stores.
