Approaches to activity regulation of Са2+-depot of sarcoplasmic and endoplasmic reticulum
N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Russia, 119334, Moscow, Kosygin St. 4, +74959397409, firstname.lastname@example.org
The numerous processes at biological cells shall be governed by ion flows in cytoplasm. The basic contribution to changing of the cytoplasmic Са2+ concentration bring the Са2+-depot of sarcoplasmic (SR) and endoplasmic reticulum (ER), and also the plasma membrane proteins, which are integrated to plasmalemma. These membrane proteins form the ion-channels that conduct Са2+ from extracellular medium. The study of nature endogenic and exogenous substances direct effect to flows of Са2+, which takes part at the regulation of the muscle contraction, was held on reticulum fragments (FSR), which were obtained by differential centrifugation of homogenates of rabbit skeletal muscles. The study of the synthetic substance (BAS) effects to ER activities, were held on whole cells - cells of Ehrlich ascetic carcinoma (EAK), which were insulated from mice body after EAC development. These BAS influenced to ER Са2+ flows by indirect actions through the metabolic pathways. By the potentiometric рН-method it was shown that the activity of main components FSR - Са2+-ATPase and Са2+- channel of ryanodine receptor (RyR), shall be governed by free fatty acids (FFA), ions of Са2+ and Mg2+, caffeine (1,3,7-trimethilksantin). The effects are maximal when combined exposures were used. 5-10 mM caffeine reduced the accumulation efficiency of Са2+ by Са2+-ATPase to the FSR lumen, because the RyR-channels were activated. The influence of caffeine increased in the presence of 2 mM Mg2+ and FFA, and it is reduced when FFA were extracted from FSR. This treatment changed the passive permeability of FSR for Са2+ due to of influences to the lipid phase of membranes. It is known that the activation of RyR Са2+-channel leads to curvature change of biomembrane and hence, to the change of bilayer organization . Restructure of lipid phase of bilayer has been shown in works with phospholipid liposomes when action of synthetic BAS: melafen and phenoksan . It was disclosed that dose-dependent influence of such BAS for the whole isolated cells EAK is directed to protein components of membrane - the purinergic receptors, also. These actions were mediated through the metabolic pathways. The releasing of Са2+ to cytoplasm occurred, from intracellular Са2+-depot - ER, containing Са2+-ATPase and the inositoltrisphosphate receptor, which forms the Са2+-channel. And through Са2+-channels of compensatory entry, which were built into the plasmalemmal membrane. Conclusion: it is possible to regulate of of SR and ER activity by the endogenic and exogenous materials.
1. Chen W., Kudryashev M. Structure of RyR1 in native membrane. // Second Russian international conference “Cryo-electron microscopy. 2019: achievements and prospects” Lomonosov Moscow State University (MSU) June 2 – 5, 2019 pp. 36-37.
2. Archipova G.V., Burlakova E.B., Krivandin A.V., Pogoretskaya I.L. Phenosan-acid influence to phospholipid membrane. // Neurochemistry volume 13, 1996. P. 128-132 (in Russian).