Na+-H+ exchange and Na+-dependent transport systems in streptozotocin diabetic rat kidneys.

The streptozotocin-induced diabetic rat was used to test the hypothesis that Na+-H+ exchange activity in the proximal tubule luminal membrane would be increased in association with renal hypertrophy, altered glomerular hemodynamics, enhanced filtered load and tubular reabsorption of Na+, and stimulated Na+ pump activity in the basolateral membrane, previously reported characteristics of this experimental animal model. Amiloride-sensitive H+ gradient-dependent Na+ uptake and Na+ gradient-dependent H+ flux were increased in brush-border membrane vesicles from the streptozotocin-treated animals. Na+ gradient-dependent uptakes of phosphate, D-glucose, L-proline, and myoinositol were decreased in the drug-induced diabetic animals. These membrane transport alterations were not found when the streptozotocin-diabetic animals were treated with insulin.