The effects of superoxide anion on intracellular Ca2+ concentration and contractility in cultured bovine aortic smooth muscle cells / 中国药理学通报

ABSTRACT

AIM　To study the effects of superoxide anion (O.2) on Ca2+ homeostasi and contractility in cultured bovine aortic smooth muscle cell. METHODS　Using Fura-2 fluorescence technique to determine Ca2+ level and collagen gel contraction system to analyze muscle contractility. RESULTS　ATP (10 μmol*L-1 )-induced Ca2+ transient was smaller in xanthine oxidase treated cells(X/XO) than control. The mean peak increment of ［Ca2+］i(△［Ca2+］i peak) and the time integral of the elevated ［Ca2+］i(∫△［Ca2+］i dt) for 5 min were decreased from (206.1±10.2) to (147.4±14.7) nmol·L-1,and from (12.2±0.5) to (9.8±0.8) μmol·L-1·s-1. Δ［Ca2+］i peak induced by thapsigargin（1 μmol·L-1 ）in Ca2+-free solution was not affected by X/XO, but was decreased from (27.3±1.0) nmol·L-1 to (13.5±1.0) nmol·L-1 in Ca2+-containing solution because of the activation of CRAC(△［Ca2+］i CRAC). X/XO accelerated the velocity of thapsigargin-induced Ca2+ leak from (78.7±3.4) s to (64.8±4.40) s. Gel contraction area in X/XO-treated cells induced by ATP or thapsigargin (in Ca2+ free solution and in Krebs solution)was decreased from 23.6%±4.6% to 7.4%±0.2%, from 3.5%±0.6% to -1.0%±0.5%, and from 7.9%±1.4% to -0.5%±0.7%, respectively. CONCLUTION　O.2 attenuats smooth muscle contraction by impairing some of Ca2+ mobilization pathways.