The tubular vacuolation process in amphibian skeletal muscle

摘要: The exposure of amphibian muscle to osmotic shock through the introduction and subsequent withdrawal extracellular glycerol causes ‘vacuolation’ in transverse tubules. Such manoeuvres can also electrically isolate tubules from surface (‘detubulation’), particularly if followed by exposures high [Ca2+] and/or gradual cooling. This study explored factors influencing vacuolation Rana temporaria sartorius muscle. Vacuole formation was detected using phase contrast microscopy trapping or otherwise lissamine rhodamine dye fluorescence within such vacuoles. preparations were examined electron microscopy, for penetration into tubular vacuoles horseradish peroxidase introduced following procedures. These comparisons distinguished first time two types vacuole, ‘open’ ‘closed’, whose lumina respectively continuous with detached remaining space. formed close between Z-lines, but subsequently elongated along longitudinal axis fibres. suggested an involvement membrane material; latter appeared concentrated around Z-lines electron-micrograph stereopairs thick sections. ‘Open’ produced a glycerol-loaded fibre at stage when one would expect net water entry intracellular suggests that vacuole requires active fluid transport response swelling. ‘Closed’ only exposed cooling initial shock. Their densities similar those shown not so treated, suggesting both resulted single process initiated withdrawal. However, ‘closure’ took place well after vacuoles, over 25 min Its course closely paralleled development detubulation reported recently. It irreversible, reversibility formation. findings identify electrophysiological ‘detubulation’ striated initially reversible open is compatible some normal responses physiological stresses as fatigue, whereas irreversible closed might be expected pathological situations dystrophic