Dietary NaCl-induced hypertension in uninephrectomized Wistar-Kyoto rats: Role of kidney function

This study tests the hypothesis that combination of unilateral nephrectomy and a high sodium chloride (NaCl) diet causes hypertension in otherwise nor motensive Wistar-Kyoto (WKY) rats and that this hypertensive response is du e to a deficit in the remaining kidney's function. Four-week-old male WKY r ats underwent either a right nephrectomy or a sham operation. Two weeks lat er, the groups either were switched to a high (8%) NaCl diet or remained on the basal (0.72%) NaCl diet. At ages 3 and 6 months, hemodynamic parameter s and renal excretory responses were measured, in the conscious animals, be fore and after administration of a 30-min isotonic saline challenge (5% of body weight). The high-NaCl diet increased arterial pressure in the unineph rectomized but nor in sham-operated rats; the development of hypertension w as associated with increases in baseline renal excretion of fluid and sodiu m and diuretic and natriuretic responses to the isotonic saline challenge. The increased diuresis and natriuresis in the hypertensive WKY rats were re lated to a significant reduction in renal tubular reabsorption and an assoc iated increase in fractional excretion of fluid and sodium. The high-NaCl d iet also increased renal excretion of fluid and sodium in the sham-operated rats; however, the uninephrectomized animals excreted much more fluid and sodium than did sham-operated rats. These data suggest that the combination of unilateral nephrectomy and dietary NaCl excess causes hypertension in t he normotensive WKY rats, but the hypertensive response is not likely due t o a functional deficit in the remaining kidney.