Sodium-calcium ion exchange in cardiac membrane vesicles.
نویسندگان
چکیده
منابع مشابه
Sodium-calcium ion exchange in cardiac membrane vesicles.
Membrane vesicles isolated from rabbit ventricular tissue rapidly accumulated Ca2+ when an outwardly directed Na+ gradient was formed across the vesicle membrane. Vesicles loaded internally with K+ showed only 10% of the Ca2+ uptake activity observed with Na+-loaded vesicles. Dissipation of the Na+ gradient with the monovalent cation exchange ionophores nigericin or narasin caused a rapid decli...
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Two mechanisms of Na+ influx have been observed using synaptosomal plasma membrane vesicles purified by density gradient centrifugation from a synaptosomal hypotonic lysate. First, a 5-fold increase in uptake over basal Na+ entry occurs with 50 microM veratridine. The veratridine-dependent Na+ uptake is partially inhibited by 2 microM tetrodotoxin with an apparent time dependency of action (hal...
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The initial velocity of Ca2+ uptake via the Na-Ca exchange system in cardiac sarcolemmal vesicles is competitively inhibited by extravesicular Na+. The Hill plots for multisite competitive inhibition are nonlinear, exhibiting a limiting slope of 1 at low Na+ concentrations (less than 20 mM) and 1.6-2.0 at higher concentrations. The Ki for Na+ is approximately 16 mM. Thus, the Ca2+ binding site ...
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The ability of mature mammalian spermatozoa to maintain a co-ordinated and forward motility is dependent upon intracellular free Ca2+ being maintained within anarrow concentration range [l]. At the level of the flagellar plasma membrane this could be achieved by two systems: (a) an ATP requiring Ca2’pump; or (b) a Na+/Ca2+ antiporter. Although such plasma membrane Ca2+extrusion mechanisms have ...
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Na-Ca exchange activity in bovine cardiac sarcolemmal vesicles was stimulated up to 10-fold by preincubating the vesicles with 1 microM FeSO4 plus 1 mM dithiothreitol (DTT) in a NaCl medium. The increase in activity was not reversed upon removing the Fe and DTT. Stimulation of exchange activity under these conditions was completely blocked by 0.1 mM EDTA or o-phenanthroline; this suggests that ...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 1979
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.76.2.590