HEPATIC DENERVATION CHRONICALLY ELEVATES ARTERIAL-PRESSURE IN WISTAR-KYOTO RATS

Several lines of evidence suggest that peripheral osmoreceptors respon d to alterations in dietary NaCl by adjusting renal sympathetic nerve activity, but the impact of this reflex on the long-term regulation of mean arterial pressure (MAP) remains unclear. The present study teste d the hypothesis that denervation of peripheral osmoreceptors elevates arterial pressure and induces NaCl-sensitive hypertension in normoten sive rats. Hepatic denervated and sham-operated Wistar-Kyoto rats were instrumented with telemetry probes for continuous monitoring of MAP a nd heart rate. After 1 week on a basal (0.6%) NaCl diet, the rats were fed a high (8%) NaCl diet for 2 weeks. On the basal NaCl diet, MAP in hepatic denervated rats was 15+/-1 mm Hg higher than in sham-operated rats. The high NaCl diet did not significantly increase MAP above bas eline levels in either denervated or sham-operated rats, but the ampli tude of the 24-hour rhythm of arterial pressure increased significantl y more in the denervated than in the sham-operated rats. In a second e xperiment two similar groups of rats were fed a very low (0.05%) NaCl diet. Mean arterial pressure of the denervated group was significantly higher than that of the sham-operated rats on either the basal or the very low NaCl diet, but the very low NaCl diet did not affect arteria l pressure in either group. These results suggest that in the rat, alt hough hepatic osmoreceptors contribute to long-term arterial pressure regulation, they contribute much less to dietary NaCl-induced changes in arterial pressure.