Alkalinization of the incubation medium by rat and rabbit renal cortical slices

The pH of bathing media containing acetate increased substantially during a 90-min incubation of renal cortex slices from rats and rabbits and did not achieve a steady state after 5 h. Alkalinization of the medium was markedly depressed by cold (0 degree C) and nearly abolished by incubation under 100% N2. Ammonia synthesis did not appear to be an important additional source of base. Incubation of tissue from either species in acetate-free medium reduced but did not abolish base production. Acetazolamide further reduced base production by rat kidney. It was concluded that a portion of the base added to the medium by rat renal tissue reflects the operation of a transport process that separates hydrogen and hydroxyl ions and may be the same one that normally secretes hydrogen ion into tubular fluid.