Bicarbonate concentrations in the renal cortex.

Total CO2 (CO2+HCO3-) was measured in alkaline extracts of quickly frozen rat renal cortex. The mean concentration calculated for tissue water was 18.7 +/- SD 1.6 mEq/l (n = 10) when that measured in plasma water was 23.5 +/- 1.7. In other experiments (n = 6-10), the mean concentration in tissue water increased to 28.3 mEq/l after the animals were treated with benzolamide to inhibit carbonic anhydrase and to 38.1 mEq/l after they were infused with NaHCO3. On the other hand, the tissue concentration decreased to 14-15 mEq/l when they were hyperventilated or infused with HCl. Calculations based on published micropuncture data indicate that the usual intracellular concentration is 20-25 mEq/l or about twice that usually reported for skeletal muscle; and in contrast to muscle, the findings are suggestive of large variations in metabolic disorders.