Effects of taurine and enalapril on kidney function of the hypertensive glucose-intolerant rat

Background: Recent studies indicate that the coexistence of hypertension and glucose intolerance leads to impairment in saline volume-induced diuresis and natriuresis. Furthermore, taurine and enalapril affect renal function and blood pressure (BP). Therefore, we tested the hypothesis that therapy combining taurine and enalapril would confer greater antihypertensive activity and responsiveness to saline volume loading in the hypertensive glucose-intolerant (HGI) rat than either agent alone. Methods: Hypertensive (H) and HGI rats were treated from 6 weeks to 6 months with tap water containing no addition, taurine (0.25%), enalapril (15 mg/kg/day), or the taurine-enalapril combination. Hemodynamic and renal responses to an intravenous isotonic saline volume load were then determined in the conscious animal. Results: The vehicle-treated HGI rats displayed reduced saline volume-induced diuresis and natriuresis relative to their H counterparts. Although none of the three drug regimens affected BP, they were similarly effective in increasing the renal excretory responses to saline volume loading and in eliminating differences that existed between the untreated H and HGI groups. Although reduced tubular reabsorption activity contributed to the taurine- and enalapril-mediated augmentation in renal excretory function, enalapril also enhanced glomerular function. The augmentation in the glomerular filtration rate was greatest in the HGI rat treated with the combination of taurine and enalapril. Furthermore, all three drug regimens significantly reduced protein excretion in both H and HGI rats. Conclusions: Despite exerting no influence on BP, all three drug regimens were renoprotective, as indicated by the drug-mediated improvement in kidney function of the HGI rat.