[Effect of increased functional activity on the contractile function of skeletal muscle]. / Vliianie povyshennoi funktsional'noi aktivnosti na sokratitel'nuiu funktsiiu skeletnykh myshts.

The adaptation of rats to the exercise program the intensity of which corresponded to metabolic power output of 190% VO2max, did not produce any significant changes in Mg2+ and Ca2+ activated ATPase activity in the different types of skeletal muscle fibers. The increase in the cross-sectional area of glycolytic muscle fibers was due to the hypertrophy of all cellular structures, especially the srcoplasmic reticulum. The sytochrome aa3 concentration increased by 23%. The submaximal exercise program (130% VO2max) elicited a significant elevation of Mg2+ activated actomyosin ATPase activity in the oxydative-glycolytic muscles and a decrease of the latter enzyme activity in glycolytic muscles. The endurance exercise (70% VO2max) caused a small decrease in Mg2+ activated actomyosin ATPase activity in the oxydative-glycolytic muscles and an increase in the oxydative ones. The character of the adaptive response of the actomyosin ATPase in different types of skeletal muscle fibers depends on the intensity and duration of the running program.

Myocardial protection during aortocoronary bypass.

The authors analyze the results of 220 applications of internal cold cardioplegia in 136 patients with ischaemic heart disease, treated surgically by aortocoronary bypass. The operation was performed under neuroleptanalgesia and artificial circulation with hypothermia (27.9 +/- 0.2 degrees C) and haemodilution (24.9 +/- 0.3%). On the basis of clinical examination, electron microscopy of the myocardial ultrastructure, and investigation of the myocardial metabolism (contents of glucose, lactate, pyruvate, free fatty acids, catecholamines, and oxygen in arterial and venous blood flowing out of the myocardium), they come to the conclusion that internal cold cardioplegia efficiently protects the myocardium during aortocoronary bypass and secures favourable conditions for the development of anastomoses between coronary arteries and venous shunts.

[Reactive changes in the retroperitoneal brown fatty tissue in rats after adrenalectomy]. / O reaktivnykh izmeneniiakh retroperitoneal'noi buroi zhirovoi tkani u krys posle adrenaléktomii

Histological, histochemical, electron microscopic and biochemical methods were used to study the ability of retroperitoneal brown adipose tissue to steroidogenesis in 54 normal and adrenalectomized adult albino rats. The activity of glucose-6-phosphate-dehydrogenase in the adipose tissue of "brown" type was established to increase as well as the content of compounds with active carbonyl groups. The size of mtochondria was sharply increased. Biochemical analysis of the brown adipose tissue determined considerable concentration of corticosterone equal to one fifth of the average concentration of this hormone in the adrenocortical tissue. The obtained data indirectly confirm the hypothesis of possible formation of steroid hormones in the retroperitoneal brown adipose tissue in rats.