Intracellular buffering

Abstract

In the quantification of buffering the distinct roles of bicarbonate and of other buffers must be taken into account. The determination of the total non-bicarbonate buffer value, β a, in intact tissues is complicated by active pH regulation and by heterogeneity of cytoplasm with respect to β a, while heterogeneity with respect to pH in vivo could cause errors in estimates made with homogenates. Available estimates of β a are discussed, as are the individual contributions of proteins, dipeptides and phosphates. A high β a is appropriate in cells which sometimes have high rates of glycolysis, or which buffer extracellular fluid, but non-protein buffer concentrations can be well below the limits imposed by osmolarity, perhaps because buffering can upset ionic gradients.