Differences in adaptive stabilization of structures in response to stress and hypoxia relate with the accumulation of hsp70 isoforms

Abstract

The phenomenon of adaptive stabilization of structures (PhASS) develops during adaptation of the organism to intermittent restraint stress. The PhASS manifests itself in a considerably increased resistance of the heart to a broad spectrum of harmful factors. In the present work, the content of hsp70 and their role in the development of PhASS during adaptation to intermittent restraint stress and to intermittent hypoxia were studied. In adaptation to restraint stress, five hsp70 isoforms with pI ranging from 5.7 to 6.3 were accumulated in the myocardium. The heart simultaneously became strikingly resistant to reperfusion paradox and heat shock. In adaptation to hypoxia, only two hsp70 isoforms with pI about 5.8 were accumulated. The resistance to reperfusion paradox was not increased and the resistance to heat shock was increased only moderately. These data suggest a role of different hsp70 isoforms in the mechanism of PhASS as well as adaptive protection of the heart.

Protective Effects of Intermittent Hypoxic Adaptation on Myocardium and Its Mechanisms

“…But limited studies provide little agreement with this presumption. Acclimatization of rats to intermittent hypoxic exposure (40 days at a high altitude of 4,000 m) increased two hsp70 isoforms, but the resistance of the isolated perfused heart to postischemic contractile dysfunction and creatine kinase release was not improved [27]. In another study [28], two weeks of exposure to a simulated altitude of 5,000 m did not affect the expression of hsp70 mRNA in the heart.…”

Heat-shock proteins and cardioprotection

“…Adaptation of animals to periodic moderate stress was shown to increase heart resistance to ischemia and reperfusion and toxic concentrations of catecholamines and calcium. Various cellular structures of the heart (mitochondria, elements of the sarcoplasmic reticulum, and nuclei) differ in extremely high resistance to autolysis [1][2][3][4][5]22]. The contents of mRNA and HSP70 in the heart in adapted animals are increased [5].…”

Comparative analysis of polypeptides in the heat shock proteins synthesized in the myocardium of Wistar and August rats

“…The exposure of Wistar and August rats to thermal stress resulted in the synthesis and accumulation in their hearts of several polypeptides with molecular weights of 71-72 kD, which had previously been identified as hsp-70 [7]. In the Wistar myocardia, hsp-70 were represented by at least five polypeptides isofocusing in a pH gradient range of approximately 5.7-6.2, and the polypeptides present in greatest amounts were those with pI values of 5.8 and 6.2 ( Fig.…”

“…For our comparative study of hsp-70 gene expression in the myocardium of rats from two genetically distinct populations we chose to analyze the polypeptide compositions of hsp-70 synthesized in August and Wistar rat myocardia in response to thermal stress because this is the most c o m m o n inducer of all hsp-70 genes [4], and also in response to repetitive immobilization stress because this had been shown to induce selectively the synthesis of particular hsp-70 polypeptides [7]. Figure 1 shows pooled results obtained with the two-dimensional gel electrophoresis of hsp-70 proteins synthesized in the myocardia of Wistar (2 and 3) and August (5 and 6) rats in response to the thermal and immobilization stress.…”