Changes of enzyme activities in the myocardium and skeletal muscle fibres of cardiomyopathic hamsters.A cytophotometrical study

Abstract

Cytophotometrical measurements of enzyme activities were performed in the myocardium and skeletal muscle fibres from normal and cardiomyopathic hamsters (BIO 8262) during ageing from 12-14 to 120-190 days. Myocardium as well as vastus lateralis muscles of cardiomyopathic hamsters showed changes in enzyme activities. The skeletal muscle fibres were typed into slow-oxidative, fast-oxidative glycolytic and fast-glycolytic to investigate fibre type-related changes in muscles of cardiomyopathic hamsters. The following myopathic changes were mainly found: Myofibrillic ATPase was depressed in the myocardium of both ventricles in all investigated age stages. The ATPase activity of the right ventricle was more decreased than that of the left one. Additionally, a metabolic shift was observed in myocardium and slow-oxidative muscle fibres at the onset of clinical symptoms, which appeared from day 150 to day 190. During the period from 42 up to 190 days of life an increase of oxidative (succinate dehydrogenase) activity was measured in the myocardium of both ventricles and in slow oxidative fibres of vastus lateralis muscle as a proximal muscle. At earlier ages, the fast fibres of myopathic vastus lateralis muscle showed higher glycolytic (glycerol-3-phosphate dehydrogenase) activity than those of normal muscles. However, at the age of 120-190 days the metabolic profile of fast fibres was normalized. In gastrocnemius muscle as a distal muscle no changes of enzyme activities were measured, suggesting the investigated hereditary myopathy effected proximal, but not distal muscles.