Evidence from renal proximal tubules that HCO3- and solute reabsorption are acutely regulated not by pH but by basolateral HCO3- and CO2.

ABSTRACT: Respiratory acidosis, a decrease in blood pH caused by a rise in [CO(2)], rapidly triggers a compensatory response in which the kidney markedly increases its secretion of H(+) from blood to urine. However, in this and other acid-base disturbances, the equilibrium CO(2) + H(2)O HCO(3)(-) + H(+) makes it impossible to determine whether the critical parameter is [CO(2)], [HCO(3)(-)], and/or pH. Here, we used out-of-equilibrium CO(2)/HCO(3)(-) solutions to alter basolateral (BL) [HCO(3)(-)], [CO(2)], or pH, systematically and one at a time, on isolated perfused S2 rabbit proximal tubules. We found that increasing [HCO(3)(-)](BL) from 0 to 44 mM, at a fixed [CO(2)](BL) of 5% and a fixed pH(BL) of 7.40, caused HCO(3)(-) reabsorption (J(HCO(3))) to fall by half but did not significantly affect vo

SUBMITTER: Zhou Y 

PROVIDER: S-EPMC553318 | biostudies-literature | 2005 Mar

REPOSITORIES: biostudies-literature