[Increased natriuresis in narcotized and waking rats with spontaneous hypertension]

The influence of acute volume-salt loading on renal excretory function and hemodynamics was studied in urethane-anesthetized and conscious immobilized, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats on osmotic diuresis. The SHR have been shown to response to the intravenous sodium chloride load with exaggerated natriuresis as compared with the WKY group. The increase in natriuresis in the SHR did not depend on diuresis changes but was due to the increased urinary sodium concentration. Blood pressure changes after sodium chloride load were greater in the WKY than in the SHR group, which may be associated with restricted responsiveness of the cardiovascular system in the SHR.