Author(s): NascimentoGomes G, Zaladek Gil F, MelloAires M
Abstract Share this page
Abstract Renal acid excretion and proximal and distal nephron acidification were evaluated 20 days after induction of diabetes, in rats, by intraperitoneal injection of streptozotocin (45 mg/kg). Titratable acidity in urine was measured by microtitration and ammonium excretion (NH4+) by spectrophotometry. Proximal tubular acidification was evaluated by the kinetics of reabsorption of perfused HCO3-. Distal nephron acidification was evaluated by measuring urine - blood pCO2 differences under alkaline overload. The net acid excretion (titratable acidity + NH4+ - HCO3-) was higher (p < 0.001) in diabetic rats (9.82+/-0.65 micromol/min/kg, n = 26) than in the control group (6.34+/-0.14, n = 24). Proximal HCO3- reabsorption was also higher (p < 0.001) in diabetic rats (8.38+/-0.11 nmol/cm2/s, n = 12) than in the control group (2.30+/-0.10, n = 22); however, evaluation of distal nephron H+ secretion by urine - blood pCO2 methodology was similar in both groups. We concluded that in rats with induced diabetes mellitus there is an increased rate of proximal HCO3- reabsorption, possibly effected by a higher density of Na+/H+ antiporter in the luminal membrane of the proximal tubule and by an increased proton-motive force of the H+ secretory mechanism. The higher rates of H+ secretion generate lower stationary proximal luminal pH and probably maintain the blood pH within the physiological range.
This article was published in Kidney Blood Press Res
and referenced in Journal of Diabetes & Metabolism