Correlation of calcium-activated ATPase activity, lipid peroxidation, and the contractile response of rabbit corporal smooth muscle treated with in vitro ischemia

Oxygen and glucose are critical to support the survival and integrity of al l smooth muscles. Hypoxia alone has been demonstrated to suppress the contr actile response of corporal smooth muscle, and one might expect simultaneou s deprivation of oxygen and glucose (in vitro model of ischemia) to exert m ore serious damage to corporal smooth muscle contraction. The effect of in vitro ischemia on the pharmacological responses of isolated rabbit corporal smooth muscle was correlated with the level of tissue lipid peroxidation. The effects of in vitro ischemia were as follows: (1) In vitro ischemia res ulted in an 85% reduction in the contractile response to phenylephrine; (2) more than a 50% reduction in the activity of thapsigargin-sensitive calciu m-activated ATPase activity of the microsomes (sarcoplasmic reticulum [SR]) ; (3) more than a fourfold increase in the tissue concentration of thiobarb ituric acid reactive substances (TBARS) (level of lipid peroxidation). In c onclusion, stimulation of lipid peroxidation in part may be responsible for the decrease in thapsigargin-sensitive calcium-activated ATPase activity o f the SR (SERCA), and the correlated decrease in the contractile response t o phenylephrine in response to ischemia. (C) 1999 Elsevier Science Inc. All rights reserved.