[ATPase activity and processes of calcium transport in membranes of sarcoplasmic reticulum of skeletal muscles with E-avitaminotic dystrophy]. / Mg 2+, Ca 2+--ATPaznaia aktivnost' i protsessy transporta kal'tsiia v membranakh sarkoplazmaticheskogo retikuluma skeletnykh myshts pri E-avitaminoznoi distrofii.

Peculiarities of functioning of the sarcoplasmic reticulum muscles membranes with E-avitaminotic distrophy were studied. It was determined that the level of ATP-dependent consumption of Ca2+, value of the Mg2+, Ca2+-ATPase activity and an amount of the intermediate phosphorylated product forming in the reaction of ATP hydrolysis decrease. The rate of this product formation in the sarcoplasmic reticulum of the distrophic muscles is inhibited as compared to normalcy. Elimination of Ca2+ into calcium-free medium from the vesicular membranes of the reticulum preliminarily loaded with Ca2+ occurs more rapidly under dystrophy than in normalcy. The data obtained evidence for a disturbance of mechanism of Ca2+ active transport and for an increase in the membrane permeability for Ca2+ in the membranes of the dystrophic muscles sarcoplasmic reticulum. A problem is considered on a dependence of the skeletal muscles observed in the reticulum under dystrophy of the functional changes on the membrane structure, in particular on their lipid composition.

[Solubilization and reconstruction of microsomal AMP-deaminase from skeletal muscles]. / Soliubilizatsiia i rekonstruktsiia mikrosomal'noi AMP-dezaminazy skeletnykh myshts.

Microsomal AMP-deaminase was solubilized by 0.5 M KCl after treatment of microsomal membranes with 0.12 M KCl. Using disc-electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate one major protein component (mol. weight about 90 000) and three minor ones with molecular weights of 110 000, 80 000, and 60 000 were found in the soluble fraction. In addition to proteins, the fraction was found in the soluble fraction. In addition to proteins, the fraction was found to contain a small amount of phospholipids. The deaminase found in the solution may be reconstructed into the membranes at a decrease in KCl concentration, part of enzyme being bound in the inactive form under excess of the soluble fraction. Deaminase binding to the membranes is unaffected by the changes within the pH range of 6.2--7.8 and temperature range of 4--10 degrees C. It is assumed that AMP-deaminase is bound to other membrane components by electrostatic bonds.

[Biochemical and functional changes in skeletal muscles with electrostimulation]. / Biokhimichni i funktsiunal'ni zminy v skeletnykh m'iazakh za elektrostymuliatsii

Electrostimulation of rabbit muscles for 18 days is accompanied by a disturbance in certain biochemical indices and functional state of the muscles. This is confirmed by a decrease in ATP content, intensity of Ca2+ uptake by the sarcoplasmatic reticulum fragments, by a drop in exitability (by the indices of rheobase and chronaxia) as well as by a change in the structure of muscular fibres components, motor axons, motor nerve endings and sciatic nerve stems. Less developed changes are observed when electrostimulation is performed for 5 days and twice for 5 days, including the period of rest. In this case the changes in Atp content and visual deviations in the muscles structure are absent and only the ability of the sarcoplasmatic reticulum fragments to Ca2+ uptake decreases insignificantly and the muscles excitability increases. Administration of ATP and simultaneous electrostimulation for 5 days normalize the disturbed Ca2+ uptake and preserve the higher excitability, that makes it possible to consider this regime of training to be the most acceptable.