Effect of short- and long-term immobilization stress on Ca-pumping function of the sarcoplasmic reticulum and resistance of the heart to Ca++ excess

Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 2, pp. 122–124, February, 1990.     

Stress-induced modification of the sarcoplasmic reticulum Ca transport system of the heart and its resistance to endogenous damaging factors

Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy or Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 9, pp. 271–274, September, 1989.     

Adaptation to stress enhances the resistance of the calcium pump in rat myocardial sarcoplasmic reticulum

The development of adaptation during stress is studied. At the early stages, adaptation exerts no protective effect: the activities of superoxide dismutase and catalase and the resistance and the Ca-transporting system of the myocardial sarcoplasmic reticulum to heat inactivation and high calcium concentrations decline. At the end of adaptation, superoxide dismutase and catalase activities increase, the function of the sarcoplasmic reticulum Catransporting system is improved, and the resistance of this system to high Ca concentrations increases compared with that in the control (1.4-fold) and during the early stages of adaptation (1.6-fold). The resistance to heat inactivation increased 1.5-fold compared with the control. Three days after the completion of adaptation, the activities of these enzymes and the resistance of Ca transport to heat inactivation and high Ca concentrations are lower than immediately after adaptation, but higher than in the control group and during the early adaptation period. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 123, No. 3, pp. 272–276, March, 1997     

Intracellular localization of the caffeinesensitive form of Ca++-dependent ATPase of the sarcoplasmic reticulum

Bulletin of Experimental Biology and Medicine -     

Some properties of the calcium pump of the sarcoplasmic reticulum of the skeletal muscles of rabbits with hypercholesteremia

Fragments of sarcoplasmic reticulum (SR) isolated from the skeletal muscles of rabbits with marked atherosclerosis have impaired ability to accumulate Ca⁺⁺. A decrease in the efficiency of the transport process, expressed as a decrease in the Ca/ATP ratio, is accompanied by activation of Ca-ATPase and by a simultaneous increase in the rate of outflow of Ca⁺⁺ from SR. The temperature dependence of Ca-ATPase, plotted between Arrhenius coordinates, normally has an inflection at 20–21°C, but in hypercholesteremia the graph becomes a straight line. Meanwhile the cholesterol/protein ratio in membrane preparations of SR rises sharply in atherosclerosis. The Ca-ATPase of native membranes has an activation energy (E_a) of 15.6 and 28.7 kcal/mole in regions above and below the inflection respectively. The Ca-ATPase of membranes containing an increased amount of cholesterol has an activation energy of 19 kcal/mole over the whole range of temperatures investigated. It is suggested that the cholesterol level in membrane preparations changes not only the physicochemical characteristics of the membranes, but also the enzymic properties of transport ATPase.Laboratory of Molecular Pathology and Biochemistry, Institute of General Pathology and Pathophysiology, Academy of Medical Sciences of the USSR, Moscow. Department of Biochemistry, M. V. Lomonosov Moscow University. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 7, pp. 32–35, July, 1978.     

Disturbances of the Ca++ transport enzyme system in membranes of the sarcoplasmic reticulum caused by hydroperoxides of phospholipids and of fatty acids

The hydroperoxide (HP) of phosphatidylethanolamine, if added to a suspension of vesicles of the sarcoplasmic reticulum (SR), was shown to have a weak activating effect on Ca-dependent ATPase and to increase the permeability of SR membranes for Ca⁺⁺, measured during activity of the enzyme. HP of linoleic acid did not affect the parameters of the Ca⁺⁺ transport enzyme system, the activity of Ca⁺⁺-dependent ATPase, the Ca/ATP ratio, or the rate of outflow of Ca⁺⁺ in SR membranes on account of the low level of its incorporation into SR fragments. It is concluded that among the primary molecular peroxidation products (HP of free fatty acids, HP of phospholipids), induced both in vitro (by the Fe⁺⁺+ascorbate system) and in vivo (ischemia, avitaminosis-E), only phospholipid HP is an effective modifier of Ca⁺⁺ transport in SR membranes.This was a combined research project of the M. V. Lomonosov Moscow State University and the I. M. Sechenov First Moscow Medical Institute.Laboratory of Physical Chemistry of Biomembranes, M. V. Lomonosov Moscow State University. Laboratory for Transplantation of Organs and Tissues, Academy of Medical Sciences of the USSR, and Department of Operative Surgery and Topographic Anatomy, I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kovanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 2, pp. 145–149, February, 1979.     

Adaptation to stress increases the resistance of the heart to adrenotoxic damage

Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 4, pp. 411–413, April, 1989.     

Activation by intracellular calcium of a potassium channel in cardiac sarcoplasmic reticulum

The effects of low (pCa 7.5 to 3) concentrations of intracellular calcium ion on a single potassium channel in the sarcoplasmic reticulum of canine heart ventricular muscle were investigated using a planar lipid bilayer technique. The low concentrations were obtained by mixing EGTA and calcium chloride. By varying the pCa of the cytoplasmic face between 3 to 7.5, two novel effects were observed. First, an increase in the intracellular Ca²⁺ concentration produced an increase in the unit current amplitude of open states; the voltage-current relationship was ohmic at these concentrations. Second, an increase in the Ca²⁺ concentration increased the open probability. Both these effects of Ca²⁺ were dose-dependent, and were consistently observed in all channels tested. Thus, the SR potassium channel observed appears to belong to the class of Ca²⁺ -activated potassium channels.     

Ischemic damage to the sarcoplasmic reticulum of skeletal muscles: The role of lipid peroxidation

The development of ischemia was shown to be accompanied by inhibition of the Ca²⁺ enzyme transport system (ETS) (a decrease in the Ca²⁺/ATP ratio and in activity of Ca²⁺-dependent ATPase), which correlates with accumulation of the primary and secondary molecular lipid peroxidation products (POL) in vivo and in the membranes of the sarcoplasmic reticulum (SR) of the skeletal muscles. Administration of antioxidants (2,6-di-tert-butyl-4-methylphenol, -tocopherol) prevents activation of POL in the ischemic muscle and partially protects the Ca²⁺ ETS against injury. Restoration of the blood flow after prolonged ischemia leads to further inhibition of the Ca²⁺ ETS while the concentration of POL products remains unchanged.A joint research project of the M. V. Lomonosov Moscow State University and the I. M. Sechenov First Moscow State Medical Institute.Laboratory of Transplantation of Organs and Tissues, Academy of Medical Sciences of the USSR. Department of Operative Surgery and Topographical Anatomy, I. M. Sechenov First Moscow Medical Institute. Laboratory of Physical Chemistry of Biomembranes, M. V. Lomonosov Moscow State University. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kovanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 6, pp. 683–686, June, 1977.