Insulin increases vascular smooth muscle recovery from intracellular calcium loads

Abstract

Insulin has previously been shown to attenuate vasoconstrictor responses to pressor agonists and accelerate vascular smooth muscle relaxation and vascular smooth muscle Ca2+ efflux. To further determine the role of insulin in regulating vascular smooth muscle Ca2+, quiescent A7r5 cultured vascular smooth muscle cells and human vascular smooth muscle cells were incubated with or without 10-7 or 10-8 M insulin for 1 hour and then loaded with fura 2-AM; intracellular Ca2+ responses to and rates of recovery from angiotensin II (200 nM) and arginine vasopressin (AVP) (10 μM) were studied fluorometrically in stirred suspension. Insulin (10-7 M) caused an increase in the peak intracellular Ca2+ response to angiotensin II (peak/baseline×100=469±96 versus 288±74, P