Proton efflux from corn roots induced by tripropyltin.

Tripropyltin restores medium acidification by washed corn root tissue in which electrogenic H(+) efflux has been blocked by ATPase inhibitors or injury. However, the restored H(+) efflux is not electrogenic and will not drive K(+) influx, and, by itself, tripropyltin is inhibitory to K(+) influx. Tripropyltin elicits a 5-fold increase in endogenous chloride efflux, and Cl(-)/OH(-) exchange can, thus, account for the observed acidification of the medium. This explanation cannot be applied equally to the acidification produced by the K(+)/H(+) exchanging ionophore nigericin.