Correlation between antioxidant and anti-ischemic effects of some energy-yielding compounds

Abstract

Shifts of LPO potential of the myocardial tissue were assessed by measuring the kinetics of chemiluminescence (ChL) of products of iron-induced LPO in homogenates of intact and ischemic rat myocardium [1]. The parameters recorded are linked with particular reactions of LPO. The intensity of the quick flash (the amplitude of the quick flash, in mM) is proportional to the content of lipid hydroperoxides in heart tissue homogenate, the latent period characterizes the potential of the endogenous antioxidant system, and the velocity of the initial region of the slow flash (tangent of the angle a) denotes the LPO process at the stage of branched chain reactions. The light sum of the slow flash, determined as the area beneath the curve of ChL of the slow flash (in mm2), characterizes the total yield of peroxide radicals in branched chain reactions. Experiments were carried out on noninbred male rats weighing 180-200 g. Acute myocardial ischemia was induced by ligating the anterior descending branch of the left coronary artery. The effect of the test substances on changes in pH of the outflowing perfusion fluid and the duration of myocardial contractile activity were studied on a model of metabolic acidosis, on the isolated rat heart [5]. The integral anti-ischemic action of the test substances was assessed by studying the results of determination of the size of the zone of necrosis ~nd the zone of myocardial ischemia by means of an indicator-differential method [6] 4 h after ligation of the coronary artery. Substances for testing were injected intravenously into the femoral vein in the course of 60 min after ligation of the coronary artery (the doses and number of experiments in the series are given in Table 1). The study of the dynamics of LPO development depending on the duration of ischemia showed that initial changes in LPO were observed after 60 min of ischemia caused by ligation of the coronary artery, and the changes reached a peak 2-3 h after occlusion [3]. It is important to note the increase taking place in acute myocardial ischemia both of LPO products, namely hydroperoxides of malonic dialdehyde, and of the LPO potential, reflected in the rate of rise and the light sum of the flash of iron-induced ChL from 285 _ 38 mm 2 in the intact myocardium to 487 __. 84 mm 2 in the ischemic myocardium. A similar picture also was observed in thermal ischemia of the heart, but unlike in acute coronary ischemia, in these experiments the period of induction of the slow flash of ChL was shortened.