Nadcin in a dose of 90 mg/kg administered to dogs with subacute stage of ischemia-reperfusion myocardial injury immediately after blood flow resumption normalized redox potential of cardiomyocytes and mitochondria and restored the total content of adenyl and pyridine nucleotides. The decrease in the synthesis of ATP and pyridine nucleotides and reduction of the redox potential of the energy supply system were inversely related to the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area and nonischemic region. Nadcin abolished the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area of the right ventricle, nonischemic region, and ischemic area of the left ventricle (by 2.4, 2.9, and 1.52 times, respectively) and normalized bioenergetic activity of cardiomyocytes during ischemia-reperfusion myocardial injury.
The development of immediate and delayed long-term resistance to hypoxia during a course of intermittent normobaric hypoxia (15 daily sessions of alternating exposure to 10% O2 and atmospheric air for 1 h) correlated with biphasic expression of HIF-1α in neocortex of hypoxia-intolerant rats, which suggests involvement of this protein factor not only in the formation of long-term adaptation, but also in triggering immediate adaptation to hypoxia. Both processes develop under conditions promoting down-regulation of oxidative modification of LDL and increasing tolerance of biological membranes to hypoxia in the absence of activation of the free radical processes, which therefore do not trigger HIF-1α expression under these conditions. Neither cytokines nor NO are the inducers of immediate adaptation, and they are not related to HIF-1α expression during the early post-hypoxic period. In contrast, long-term adaptation in response to the course of intermittent normobaric hypoxia develops against the background of enhanced NO production, activation of pro- and anti-inflammatory factors, and expression of VEGF, the marker of angiogenesis. Therefore, all these factors can promote activation of transcription processes required to form the long-term adaptation.
Experiments with hybrid myocardial fibers showed that abnormalities of actin (basic protein of fine sarcomer threads) are responsible for reduced contraction rate, decreased developed force, and low efficiency of cardiomyocyte contraction in chronic heart failure caused by dilatation and ischemic cardiomyopathies and infective allergic myocarditis. Wastefulness of the contractile process in cardiomyocyte under conditions of pronounced energy deficit play a key role in progression of chronic heart failure. Hence, actin hypothesis of reduced contractile activity of myocardial contractile protein system in acute heart failure transforms into the actomyosin concept in chronic heart failure.
The system of energy supply in the myocardium of the left and right ventricles did not recover after short-term circulatory disturbances. ATP synthesis decreased in parallel with activation of poly-(ADP-ribose)-polymerase in the ischemic region of the right ventricle, extra-ischemic region, and in the left ventricle by 5.85, 5.4, and 2.2 times, respectively. Intravenous injection of NAD immediately after blood flow resumption in the subacute period of ischemia-reperfusion damage virtually completely normalized the pool of adenine nucleotides, energy change of the adenine nucleotide system, and phosphorylation potential. Exogenous NAD inhibited activity of poly-(ADP-ribose)-polymerase in the ischemic region of the right ventricle, extra-ischemic region, and in the ischemic region of the left ventricle by 2.4, 2.9, and 1.52 times, respectively. We hypothesize that NAD acts as a regulator of signal mechanism of apoptosis induction during ischemia-reperfusion damages to the myocardium.
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