UNMASKING THE MITOCHONDRIAL K-H EXCHANGER - TETRAETHYLAMMONIUM-INDUCED K+-LOSS

Mitochondria respiring in media containing 80 mM tetraethylammonium ions lose all of their endogenous K+ within 7 minutes. K+-loss is associated with uptake of tetraethylammonium ions. K+ efflux under these conditions is energy-dependent and electroneutral. It is concluded that tetraethylammonium uptake unmasks the endogenous K H exchanger. Considered in relation to the chemiosmotic theory, these results support the existence of a carrier-brake" mechanism which modulates K H exchange to maintain volume homeostasis in vivo. © 1979."