Simultaneous Determination of Proton Concentration in Two Compartments

Abstract

Recently, elucidation of the role that cytoplasmic ions, such as calcium and protons, play in metabolic regulation has occupied considerable interest. Studies of this role have been facilitated by the development of procedures for trapping spectrally sensitive ion indicator dyes in the cell (1, 2). These methods have been limited generally to cytosolic measurements, as few means are available for measuring ions within other subcellular compartments of the intact cell. Since the transport of many metabolites across the inner mitochondrial membrane requires an ion gradient, and because these gradients play a vital role in energy conservation, a means for measuring matrix pH in intact cells would be useful.