Ion Transport Processes in Corn Mitochondria

Abstract
The local anesthetic dibucaine inhibited respiration-dependent contraction mediated by the K+/H+ antiport system of isolated corn mitochondria. Respiration declined concurrently. Nigericin, an exogenous K+/H+ exchanger, restored ion efflux in dibucaine-blocked corn mitochondria. Dibucaine inhibited ion efflux via blockage of the K+/H+ antiport. Dibucaine also inhibited proton influx facilitated by protonophores and by the ATPase complex during state III respiration. These results are discussed in relation to the mechanism by which dibucaine inhibits proton translocation across the inner mitochondrial membrane.