Membrane potential of mitochondria in intact lymphocytes during early mitogenic stimulation

Abstract

1. The mitochondrial membrane potential (Δψ(m)) in intact lymphocytes was calculated by measuring the distribution of radiolabelled methyltriphenylphosphonium cation. The value obtained was 120 mV. 2. The pH gradient across the mitochondrial membrane in situ (ΔpH(m)) was estimated to be 73 mV (1.2 pH units). Thus the electrochemical gradient of protons was about 190 mV. 3. Addition of the mitogen concanavalin A did not alter Δψ(m), showing that, if movement of Ca2+ across the inner membrane of lymphocyte mitochondria occurs when concanavalin A is added, it is accompanied by charge-compensating ion movements.