Properties of the calcium-extruding mechanism of liver cells.
1. The movements of Ca2+ between liver slices and the suspending medium have been followed with a Ca2+-specific electrode and with measurements of the efflux of 45Ca. 2. A net entry of Ca2+ into the tissue occurred during anaerobiosis. Reoxygenation of the medium resulted in a net extrusion of Ca2+ which was reversed by the addition of a respiratory inhibitor (Amytal), an uncoupler of oxidative phosphorylation (pentachlorophenol) or the divalent-cation-specific ionophore, A23187. 3. The net extrusion of Ca2+ was dependent on the presence of Mg2+ in the medium, but was not prevented by ouabain or by incubation in a Na+-free medium. Extrusion was not prevented by cytochalasin B or colchicine. 4. The undirectional efflux of 45Ca required Mg2+ to attain its maximal rate, and the magnitude was not affected by the presence of ouabain or the absence of Na+ from the medium. 5. It is concluded that extrusion of Ca2+ from liver cells is a metabolically dependent transport process that occurs independently of the exchange of Na+ between tissue and medium.
D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000494:pharmacology; D051381:Rats
D000001:Calcimycin; D003571:Cytochalasin B; D008274:Magnesium; D010100:Oxygen; D003078:Colchicine; D002118:Calcium