Activity of Energy Metabolism Enzymes and the Adenylate System in Heart Chambers of a Black Sea Scorpionfish (Scorpaena porcus L.) under Acute Hypoxia

• Published in: Journal of evolutionary biochemistry and physiology Vol. 57; no. 5; pp. 1050 - 1059
• Main Authors: Kolesnikova, E. E., Soldatov, А. А., Golovina, I. V., Sysoeva, I. V., Sysoev, А. А., Kukhareva, Т. А.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.09.2021; Springer Nature B.V
• Subjects: Animal Physiology; Atrium; Biochemistry; Biomedical and Life Sciences; Blood flow; Dehydrogenases; Energy balance; Energy charge; Energy metabolism; Evolutionary Biology; Experimental Papers; Heart; Hypoxia; L-Lactate dehydrogenase; Lactic acid; Life Sciences; Malate dehydrogenase; Metabolism; Myocardium; Nucleotides; Ventricle; Black Sea; lactate dehydrogenase; hypoxia; malate dehydrogenase; fish; heart chambers; adenylate system
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/S0022093021050070

The fish heart is a unique model to compare the resistance to hypoxia of its two chambers (atrium and ventricle), which are different in the structure and functional loads. The activity of oxydoreductases malate dehydrogenase (MDH, 1.1.1.37) and lactate dehydrogenase (LDH, 1.1.1.27), as well as the parameters of the adenylate system in the heart chambers of a Black Sea scorpaena, were studied under acute hypoxia (0.9–1.2 mg O 2 ·L –1 , 90 min). Despite the leading functional role of the ventricle, MDH activity in this heart compartment tended to decrease compared to the atrium in the absence of differences in LDH activity. At the same time, the difference in the level of adenylates (ATP, ADP, AMP), total adenylate pool (AP), and adenylate energy charge (AEС) between the atrium and ventricle was statistically nonsignificant, although the absolute value of the ventricular AP was almost twice as large as the atrial AP. The AEC values of the atrium and ventricle perfused only with venous blood did not exceed ~0.7 (vs. the maximum of this parameter ~0.9–1.0), apparently reflecting the energy status of tissues initially adapted to hypoxia. Under acute hypoxia, there were found two strategies for energy metabolism transformation in the heart chambers in the form of a 2.4-fold drop in MDH activity ( р < 0.05) in the atrium and a 2.2-fold increment in LDH activity ( р < 0.05) in the ventricle. Probably, the decline in MDH activity in the atrial tissue was determined by a more passive function of this heart chamber in providing the blood flow. The exposure to acute hypoxia led to a decrease in the level of adenylate nucleotides and an AEC decline in the heart chambers, as pronounced most distinctly in the ventricular myocardium. When decreasing PO 2 , the AEC in the heart chambers shifted within quite a narrow range (from 0.7 to 0.6), indicating the retention of a certain stationary energy status achieved by inhibition of ATP consumption or demand. The putative mechanism for retaining the AEC may be based on the negative chronotropic effect of hypoxia.