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

Cytophotometrical measurements of enzyme activities were performed in the m yocardium and skeletal muscle fibres from normal and cardiomyopathic hamste rs (BIO 8262) during ageing from 12-14 to 120-190 days. Myocardium as well as vastus lateralis muscles of cardiomyopathic hamsters showed changes in e nzyme activities. The skeletal muscle fibres were typed into slow-oxidative , fast-oxidative glycolytic and fast-glycolytic to investigate fibre type-r elated changes in muscles of cardiomyopathic hamsters. The following myopat hic changes were mainly found: Myofibrillic ATPase was depressed in the myo cardium of both Ventricles in all investigated age stages. The ATPase activ ity of the right ventricle was more decreased than that of the left one. Ad ditionally, a metabolic shift was observed in myocardium and slow-oxidative muscle fibres at the onset of clinical symptoms, which appeared from day 1 50 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 myocar dium of both ventricles and in slow oxidative fibres of vastus lateralis mu scle as a proximal muscle. At earlier ages, the fast fibres of myopathic va stus lateralis muscle showed higher glycolytic (glycerol-3-phosphate dehydr ogenase) activity than those of normal muscles. However, at the age of 120- 190 days the metabolic profile of fast fibres was normalized. In gastrocnem ius muscle as a distal muscle no changes of enzyme activities were measured , suggesting the investigated hereditary myopathy effected proximal, but no t distal muscles.