Monovalent cation conductance in liposomes induced by ionophore A23187.
In the absence of divalent cations, ionophore A23187 supports low rates of monovalent cations loss (Na+ greater than K+) from unilamellar liposomes containing the sulfate salts. Monovalent cation efflux is optimal when a pH gradient (interior alkaline) is applied. The maximum observed rate of 0.56 ngion K+ . min-1 . nmol-1 A23187 is insufficient to account for the rates of K+ efflux induced by the ionophore in mitochondria (150 ngion K+ . min-1 . nmol-1 A23187). These studies therefore support the concept that A23187 induces loss of K+ from mitochondria by removal of regulating divalent cations from an endogenous K+/H+ exchanger.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D009550:Nigericin / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D008081:Liposomes; D000001:Calcimycin; D012964:Sodium; D009550:Nigericin; D011188:Potassium