Tetanus responses under rapid bath solution change: electrotonic depolarization of transverse tubules may release Ca2+ from sarcoplasmic reticulum of Rana japonica skeletal muscle.
1. Single skeletal muscle fibers were transferred from a normal Ringer solution to Na+ ion free solution, and vice versa, and tetanus responses were recorded immediately after the transfer. 2. Fractional tetanus tension recorded immediately after the displacement from the Na+ ion free solution to normal Ringer solution was dependent on fiber diameter. 3. Diffusion of Na+ ions along the transverse tubules was simulated [apparent diffusion constant was 3.11 x 10(-6) (cm2/s)]. 4. Our results suggest that the electronic spreading of membrane potential, caused by an action potential in the transverse tubules, could release Ca2+ ions from sarcoplasmic reticulum.
Department of Physiology, School of Medicine, Fukuoka University, Japan.
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Fujishiro
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H
Kawata
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004058:Diffusion; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D011898:Ranidae; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D012964:Sodium; D002118:Calcium