Blockade of Rabbit Cardiomyocyte Calcium Channels Restores the Activity of Enzyme-Substrate Complexes of the Respiratory Chain in a Model of Vibration-Mediated Hypoxia

The effect of nifedipine, a calcium channel blocker (CCB), at a dose of 7.5 mg/kg on the energy metabolism of rabbit cardiomyocytes was evaluated in a vibration-mediated model of cellular hypoxia (56 sessions of vibration 44 Hz, amplitude 0.5 mm). The energy metabolism of native heart mitochondria in a 30% tissue homogenate was assessed using a polarographic method, by recording the rate of oxygen uptake by mitochondria at 37°C in 1 ml of a saline incubation medium, equilibrated with atmospheric oxygen. In the animals exposed to vibration against the background of CCB, the rate of endogenous respiration (Ve) remained at the level of intact animals, with the amytal sensitivity increasing by 39% (p<0.05) and the malonate sensitivity decreasing by 40% (p<0.05). The malate oxidase activity at rest increased, and hyperactivation of the endogenous succinic acid oxidation system decreased as compared to the indices of the animals exposed to vibration without pharmacological protection. The observed results indicate the cardioprotective effect of nifedipine, which prevented the development of cardiomyocyte necrosis.