Control of calcium efflux from sarcoplasmic reticulum vesicles by external calcium.
نویسندگان
چکیده
منابع مشابه
Control of calcium efflux from sarcoplasmic reticulum vesicles by external calcium.
Factors modifying calcium efflux from rabbit skeletal muscle sarcoplasmic reticulum vesicles were examined after phosphate-supported calcium uptake reached steady state. Increasing external Ca”+ promoted calcium efflux by a mechanism that exhibited Michaelis-Menten kinetics; V,,, at 25” with 5 mM MgATP as substrate and 50 mM phosphate as calcium-precipitating anion was -400 nmol/mg/min and the ...
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The ability of sarcoplasmic reticulum vesicles to retain calcium following ATP-supported calcium uptake in the presence of the calcium-precipitating anions oxalate and phosphate depends on Cao (calcium ion concentration outside the vesicles) and Cai (calcium ion concentration within the vesicles). Calcium efflux rates at any level of Cai are accelerated when Cao is increased. Higher Cao at the ...
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The effects of the ionophore, X537A, and caffeine on ATP-dependent calcium transport by fragmented sarcoplasmic reticulum were studied in the absence (calcium storage) or presence (calcium uptake) of calcium-precipitating anions. The ionophore caused rapid calcium release after calcium storage, the final level of calcium storage being the same whether a given concentration of X537A was added pr...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1977
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(17)40252-3