Роль ферментов катаболизма АМР в энергетическом статусе эритроцитов в условиях их истощения по глюкозе
Role of AMP catabolism enzymes in the energetic status of erythrocytes under conditions of glucose depletion

Summary/Abstract: The adenylate metabolism determines the value of energy charge, adenylate pool and ATP concentration, with its level strongly differing in various cell types. The reasons of such differences are still not clear, moreover, role of adenylate metabolism in the regulation of intracellular ATP concentration is not fully known. Hypotheses about mechanisms of adenylate pool stabilization are based on results of mathematical modeling and require the experimental verification. It is known that AMP catabolism enzymes such as AMP-desaminase and 5’-nucleotidase are directly involved in the processes of adenylate charge and pool regulation and their activity depends on the concentration of this metabolite. It is considered that switching from AMP-desaminase pathway of AMP catabolism to 5’-nucleotidase pathway and vice versa may contribute to stabilization of adenylate charge and pool under increased energy load that leads to the reduction of ATP content. The objective of this study consisted in the experimental investigation of mechanisms of adenylate metabolism regulation in human erythrocytes as well as principles of adenylate and energy metabolism interaction in erythrocytes with varied energy charge. Сhanges in activities of catabolism enzymes such as AMP-membrane-bound (eN) and cytosolic (cN-IA) 5’-nucleotidase, AMP-desaminase (AMPDA) of erythrocytes under conditions of glucose depletion and under vibration effect on cells in the range of frequencies of 8–32 Hz, step of 4 Hz, and the amplitude of 0,5 ±0,04 mmhave been studied. Antiphase change of cN-IA and AMPDA activities in erythrocytes incubated in the medium without glucose was shown. Processes of switching of two ways of AMP catabolism create the conditions for the stabilization of energy charge and the ATP concentration stabilization though at a level below the initial one. In the erythrocytes in the medium without glucose and under vibration the antiphase change of enzyme activity was observed only under vibration at frequencies of 8 and 12 Hz. Under action of vibration in the range of frequencies 16–28 Hz, AMP catabolism mainly occurred in AMPDA pathway, cN-II, which was evidenced by sigmoid character of increase in AMPDA activity more than 2 times. Under vibration at frequency of 16 Hz cN-IA activity insignificantly changed. In frequency range of 20–28 Hz cN-IA activity was growing monotonically during 3 hours of action. Growth of cN-IA activity (50.0 ± 4.5, 34.3 ± 12.8, 39.1 ± 1.8% under the action at frequencies of 20, 24 and 32 Hz respectively, more than 2 times under action at 28 Hz) proves that cN-IA, ADODA pathway is also involved in the processes of AMP catabolism. The AMPDA activity also increased under vibration at frequency of 32 Hz, but the sigmoid character of the increase in activity was not observed. Thus, the processes of AMP catabolism intensify in erythrocytes under vibration. These processes are realized by two degradation ways. In this case, other mechanisms which are discussed in this study are likely to be involved in the stabilization of AMP level. It was shown that membrane-bound 5’-nucleotidase activity could reflect the cell lipid bilayer reorganization under the influence of external factors.

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