[Characteristic of sorption properties of skeletal muscle nuclei in the normal state and with E-avitaminotic muscular dystrophy]. / Kharakteristika sorbtsionnykh svoistv iader skeletnykh myshts v norme i pri E-avitaminoznoi myshechnoi distrofii.

Sorption properties of skeletal muscles nuclei in rabbits in normal state and with E-avitaminosis were studied using organic dyes: neutral red (cationic) and turquoise direct light-fast "K" (anionic) and the influence of calcium-modified membrane of nuclei on their sorption. The nuclear surface is established to have both positive and negative charged groups sorbing turquioise direct and neutral red, respectively. The maximum volume of the dyes binding and the dissociation constants of the membrane-dye complex are estimated. It is shown that with muscular dystrophy the number of charged groups of both signs on the nuclear surface decreases. Calcium ions decrease the cationic dye sorption both in the normal state and with dystrophy and insignificantly decrease the anionic dye with dystrophy.

[Molecular organization of Mg2+, Ca2+-ATPase of sarcoplasmic reticulum]. / Molekuliarnaia organizatsiia Mg2+, Ca2+-ATP-azy sarkoplazmaticheskogo retikuluma.

The article deals with the results of studies on the structure and properties of discrete sites in a molecule of sarcoplasmic reticulum Mg2+, Ca2+-ATPase obtained during its fragmentation in the process of its limited hydrolysis by trypsin. It is established to contain three fragments with the molecular mass of 45 000, 30 000 and 20 000 Daltons. Some properties of these fragments are determined by the amino acid analysis, inhibitory analysis with application of radiactive labels and also of immunochemical analysis. The properties show that the first fragment is hydrophobic and the others are hydrophilic; these properties show that the first fragment is hydrophobic and the others are hydrophilic; these properties determine the location of the fragments in the sarcoplasmic reticulum membrane. The fragment with the molecular mass of 45 000 Daltons forms in it a nonspecific channel as if "sewing" it, two other fragments of the Mg2+, Ca2+-ATPase are located at the outer side of the membrane, the fragment with the molecular weight of 20 000 occupying a middle position between the fragments with molecular weight of 45 000 and 30 000, thus creating a selective respect to calcium "valve" to the nonspecific channel. This discrete part of Mg2+, Ca2+-ATPase possesses the ionophoric activity. The fragment with molecular weight of 30 000 is the energy converter. The site hydrolyzing AMP is located in it. The models (hypothetic) are presented for the Ca2+ active transpprt through biological membranes with Mg2+, Ca2+-ATPase participation.

[Effect of SH-reagents on ATPase systems of rabbit skeletal muscle nuclei]. / Bliianie sul'fgidril'nykh reagentov na ATPaznye sistemy iader skelitnykh myshts krolikov.

The influence of sulfhydryl reagents on ATPase systems of rabbit sceletal muscles nuclei was studied. It is found that p-ChMB at low concentration similarly inhibits both Mg2+- and Mg2+, Ca2+-ATPases. p-ChMB at higher concentrations inhibits completely Mg2+, Ca2+-ATPase, while Mg2+- ATPase--only by 60%. N-EM is lesser specific inhibitor of SH-groups, than p-ChMB. The degree of nuclear ATPases inhibition by N-EM is practically identical. Using inhibitory analysis, two hypes of skeletal muscles nuclei SH-groups are found: easily reacting with N-EM, and those reacting with N-EM at more high concentrations, which are essential for ATPase ATP-hydrolysing activity. ATP defends Mg2+, Ca2+-ATPase, but not the Mg2+-ATPase from N-EM inhibitory action. Cysteine completely eliminates the inhibitory effect of p-ChMB on Mg2+-ATPase but only 40% on MG2+, Ca2+-ATPase. Mg2+, Ca2+-ATPase of nuclei is more sensitive to the sulfhydryl venoms action than Mg2+-ATPase.

[Electron-cytochemical study of the localization and properties of ATPases in the isolated nuclei of rabbit skeletal muscle under normal conditions and in experimental muscular dystrophy]. / Elektronnotsitokhimicheskoe issledovanie lokalizatsii i svoistv ATFaz v izolirovannykh iadtakh skeletnykh myshts krolikov v norme i pri éksperimental'noi myshechnoi distrofii.

The properties and localization of ATPase system in nuclei of skeletal muscle of normal rabbit and of those with experimental muscle dystrophy were studied by electron cytochemistry. The product of cytochemical reaction of ATP hydrolysis, which is a marker of ATPase activity localization in nuclear ultrastructures, was detected on the nuclear membrane, in chromatin and in the nucleolus, ATPase activity in the nuclei was detected in the presence of both, Mg2+ and Ca2+. Addition to the incubation medium, originally containing Mg2+, Na+ and K+, resulted in an increased formation of the product reaction in all the nuclear ultrastructures in both in the norm and under experimental muscle dystrophy. However, specific inhibitor of Mg2+, Na+, K+-ATPase--ouabain--suggests the absence in the nuclei of skeletal muscles of rabbit of transport ATPase working in the "Na-pump" system. The results of experiments with a specific complex of Ca2+--EGTA allow to suppose that Mg2+, Ca2+-ATPase of skeletal muscle nuclei of normal rabbits is localized in the nucleoplasm, whereas Mg2+-ATPase is found on the nuclear membrane. Using EGTA we failed to detected the localization of Mg2+, Ca2+-ATPase in nuclear ultrastructures upon experimental muscular dystrophy.

[Changes in the ATP-ase activity of skeletal muscle nuclei of rabbits with dystrophy and following their delipidation]. / Zminy ATF-aznoï aktyvnosti iader skeletnykh m'iaziv kroliv za dystrofiï ta pislia ïkh delipiduvannia

The level of the ATPase activity in the skeletal muscles nuclei with experimental muscular dystrophy and the sensitivity to bivalent (Mg2+, Ca2+) and univalent (Na+, K+) cations under conditions of delipidation were studied. It is established that among ATPases of the young rabbit skeletal muscles nuclei there is ATPase sensitive to monovalent cations: the presence of Na+ or K+ produces a 45% increase in its activity in some experiments as compared to the initial level. This activation is attributed to Mg2+, Ca2+-ATPase the action of which is not realized in the presence of EGTA-chelator of calcium ions. A decrease in the total ATPase activity in the skeletal muscles nuclei resulted from the experimental muscular dystrophy development occurs due to a decrease in the Mg2+, Ca2+-ATPase activity as the ability for activation by the monovalent cations is practically lost under these conditions. Delipidation of the skeletal muscles nuclei, which results in their loss of some phospholipids and cholesterin, is accompanied by the ATPase activity decrease. At the same time the nuclei ATPase activity lose its ability to activate by monovalent cations: Na+, K+. A conclusion is made that during delipidation the decrease in the total ATPase activity is due to a decrease in the activity of its Mg2+, Ca2+-part.

[Mg 2+, Ca 2+-ATPase of skeletal muscle nuclei in normal rabbits and in rabbits with experimental muscular dystrophy]. / Mg2+, Ca2+-ATF-aza iader skeletnikh m'iaziv kroliv u normii za eksperimental'noi m'iazovoi distrofii

The total ATPase activity of the rabbit skeletal muscle nuclei was established to be a sum of activities of two ATPases--Mg2+ and Mg2+, Ca2+-ATPases. The latter composes 50% of total ATPase activity for skeletal muscles nuclei of the normal rabbits and 30% for skeletal muscles nuclei of the rabbits with muscular dystrophy. Mg+, Ca2+-ATPase of the skeletal muscle nuclei is activated by calcium ions within a range of 10(-6)--10(-4) M and is inhibited with its concentration of 0.5-10(-3) M and higher. Sodium and potassium ions activate Mg2+, Ca2+-ATPase. Inhibition of Mg2+-ATPase is observed for the skeletal muscle nuclei of the rabbits in norm with the presence of 80 mM of Na+ and 70 mM of K+ in the incubation medium. Under experimental muscular dystrophy such an effect is not observed in connection with the fact that the concentration of monovalent cations in the incubation medium does not exceed 60 mM. The ATPase activity in nuclei of the rabbit skeletal muscles may be also manifested in the presence of Mn2+ greater than Ca2+ greater than Ba2+. A problem is under discussion as to substitution of ions Mg2+ by ions Mn2+, Ca2+, Ba2+ in manifestation of the Mg2+ATPase activity for the skeletal muscle nuclei of the normal rabbits and of those with experimental dystrophy.