45Ca uptake by retinal pigment epithelial cells.
Uptake of 45Ca was studied in isolated frog retinal pigment epithelial cells. 45Ca accumulation was found to be a saturable, temperature-dependent event. Kinetic analysis of this accumulation revealed two transport systems with apparent km of 2.0 and 0.3 mM. We found the presence of a Na-Ca exchanger mechanism that releases Ca2 under depolarized conditions. Light induced an increase of 45Ca uptake due to activation of the Na-K-ATPase and consequent decrease of extracellular potassium concentration.
Salceda
R
R
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D007700:Kinetics; D008027:Light; D009994:Osmolar Concentration; D010042:Ouabain / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D011190:Potassium Cyanide / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D002132:Calcium Radioisotopes; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011190:Potassium Cyanide; D002118:Calcium