Carbonic anhydrase II and IV mRNA in rabbit nephron segments: stimulation during metabolic acidosis

nephron segments: stimulation during metabolic acidosis. Am. J. Physiol. 274 (Renal Physiol. 43): F259–F267, 1998.— Carbonic anhydrase (CA) facilitates renal bicarbonate reab-sorption and acid excretion. Cytosolic CA II catalyzes the buffering of intracellular hydroxyl ions by CO2, whereas membrane-bound CA IV catalyzes the dehydration of car-bonic acid generated from the secretion of protons. Although CA II and IV are expressed in rabbit kidney, it is not entirely clear which segments express which isoforms. It was the purpose of this study to characterize the expression of CA II and CA IV mRNAs by specific segments of the nephron using semiquantitative reverse transcription-polymerase chain re-action (RT-PCR) and to determine the effect of chronic metabolic acidosis on CA expression by those segments. Individual nephron segments (usually 1–2 mm) were isolate