The antifertility agent, gossypol, releases calcium from rat liver mitochondria

Abstract 1. The effect of gossypol in the presence of K + or Ca 2+ , or both, was studied on respiration, ATPase activity, and Ca 2+ transport of rat liver mitochondria. 2. The uncoupled respiration induced by gossypol was inhibited by Ca 2+ . 3. This inhibition was lowered by the presence of Mg 2+ . ATPase activity was stimulated when gossypol and Ca 2+ were in the incubation medium, in a Ca 2+ -dose related fashion. 4. Mitochondrial Ca 2+ was released by gossypol, an effect associated with the membrane fluidity. 5. The results suggest that gossypol modifies the mitochondrial concentration of Ca 2+ .