Кінетика тетанусу musculus gastrocnemius в алкоголізованих щурів з експериментально-індукованою васкулярною ішемією задніх кінцівок за умов низькочастотної м’язової втоми
Musculus gastrocnemius tetanus kinetics in alcohol-intoxicated rats with experimentally-induced hindlimb vascular ischemia under conditions of low-frequence muscle fatigue

Summary/Abstract: Alcohol intoxication and ischemic injury of skeletal muscles often accompany each other. It is shown that patients hospitalized with chronic alcoholism develop muscle fatigue. Skeletal muscle dysfunction in alcohol-dependent patients is caused by ethanol-associated myofibrillar atrophy and metabolic disbalance, while compression-ischemic lesions result from unconsciousness of the patient, in case of taking the critical alcohol dose. Therefore, the aim of this study is to discover typical m. gastrocnemius (cap. med.) tetanic kinetics changes in alcohol intoxicated rats with experimentally induced vascular ischemia of hindlimb muscles under conditions of low-frequency progressive muscle fatigue. Experiments were carried out on 10 young male Wistar rats (149.5 ± 5.8 g) kept under standard vivarium conditions and diet. The investigation was conducted in two phases: chronic (30 days) and acute (3 hours) experiment. All surgical procedures were carried out aseptically under general anesthesia. Ishemic m. gastrocnemius (cap. med.) tetanic kinetic changes and force productivity in alcohol intoxicated rats were investigated in the isometric mode, with direct electrical stimulation. The fatigue of m. gastrocnemius (cap. med.) was evaluated by three characteristic criteria: the first sag effect, the secondary force rise, the second sag effect. There have been 10 similar experiments: 5 series in each study group with 10 tetanic runs in each series. The highest amplitude of the native m. gastrocnemius (cap. med.) tetanus relative to isoline was taken as 100% force response. The same pattern of m. gastrocnemius (cap. med.) low-frequency fatigue development was found in both rat groups under study. It is evidenced by the absence of substantial m. gastrocnemius (cap. med.) tetanus kinetics differences in alcohol intoxicated rats, compared with non-alcohol intoxicated rats during fatigue test. However, the appreciable m. gastrocnemius (cap. med.) tetanic force reduction in alcohol intoxicated rats, compared with non-alcohol intoxicated rats is found. During fatigue test, m. gastrocnemius (cap. med.) of non-alcohol intoxicated rats featured 75.0 ± 17.4% loss, that of alcohol intoxicated rats has lost 75.0 ± 17.0%, while the native one – 62.0 ± 11.3% of initial force. Contraction-relaxation cycle kinetics changes were not identified. Thus, the tetanus kinetics and tetanic force change of m. gastrocnemius (cap. med.) in alcohol intoxicated rats indicates no changes in the process of development of low-frequency muscle fatigue, compared with non-alcohol intoxicated rats. Low force productivity of m. gastrocnemius (cap. med.) in alcohol intoxicated rats compared with non-alcohol intoxicated ones directly results from alcoholic myopathy complicated by vascular ischemia.

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