| Abstract: | When rat hepatocyte monolayers were preincubated for 4 h in Hanks' salt solutions at pH 7.0, 7.4 and 8.0, and the Na+-dependent uptake of 2-(methylamino) isobutyric acid (MeAIB) was measured at the same pH values, a stimulation of transport in the order pH 7.0 less than pH 7.4 less than pH 8.0 was observed. Estimations of the intracellular pH from the distribution of DMO revealed a decrease in the internal pH during the preincubation period. The MeAIB transport velocities appear to parallel with the proton gradients across the cell membrane rather than with external (or internal) pH. Analyses of the lactate/pyruvate concentrations in the media indicated that the fall in the intracellular pH is presumably due to an enhanced glycolysis. Suppressive concentrations of system A-reactive amino acids did not prevent the decrease in the internal pH nor did they alter the metabolic data. |
