Valinomycin can depolarize mitochondria in intact lymphocytes without increasing plasma membrane potassium fluxes

Abstract

We have simultaneously measured [³H]methyltriphenylphosphonium⁺ and ⁸⁶Rb⁺ distribution across the mitochondrial and plasma membranes of pig mesenteric lymphocytes. At low concentrations the K⁺ ionophore valinomycin depolarizes the mitochondria but does not increase Rb⁺ fluxes across the plasma membrane. At high concentrations of valinomycin the plasma membrane becomes permeable to Rb⁺ and both TPMP⁺ and Rb⁺ distribution give a measure of the K⁺ diffusion potential.