Electromechanical coupling III. Estimation of the Ca storage capacity of the SR by analysing the time course of caffeine-induced tension transients of skinned muscle fibres.
The Ca uptake of the SR of a skinned fibre, which was studied with an indirect method, shows a biphasic time course. A total Ca concentration between 8 and 23 mm was accumulated in the SR by an initial fast process (tau approximately equal to 4.7 s). This Ca-uptake activity of the SR is high enough to bring about relaxation of twitch contraction in vivo. The magnitude of a subsequent slow process (tau approximately equal to 10(3) s) indicates that the total Ca storage capacity of the SR of skeletal muscle is in the order of 60-75 mm.
D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D011893:Rana esculenta; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000502:physiology*
D002110:Caffeine; D004533:Egtazic Acid; D002118:Calcium