Effects of quinine on K+ transport in heart mitochondria.
Quinine inhibits the respiration-dependent extrusion of K+ from Mg2+-depleted heart mitochondria and the passive osmotic swelling of these mitochondria in K+ and Na+ acetate at alkaline pH. These observations concur with those of Nakashima and Garlid (J. Biol. Chem. 257, 9252, 1982) using rat liver mitochondria. Quinine also inhibits the respiration-dependent contraction of heart mitochondria swollen passively in Na+ or K+ nitrate and the increment of elevated respiration associated with the extrusion of ions from these mitochondria. Quinine, at concentrations up to 0.5 mM, inhibits the respiration-dependent 42K+/K+ exchange seen in the presence of mersalyl, but higher levels of the drug produce increased membrane permeability and net K+ loss from the matrix. These results are all consistent with an inhibition of the putative mitochondrial K+/H+ antiport by quinine. However, quinine has other effects on the mitochondrial membrane, and possible alternatives to this interpretation are discussed.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004579:Electron Transport; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D009566:Nitrates / Q000494:pharmacology; D010539:Permeability; D011188:Potassium / Q000378:metabolism*; D027961:Potassium-Hydrogen Antiporters; D011803:Quinine / Q000494:pharmacology*; D014882:Water-Electrolyte Balance / Q000187:drug effects
D002352:Carrier Proteins; D009566:Nitrates; D027961:Potassium-Hydrogen Antiporters; D011803:Quinine; D011188:Potassium