Tissue norepinephrine turnover and cardiovascular responses during intermittent dehydration in the rat

We investigated the central and peripheral sympathetic responses to intermi ttent dehydration in rats. The norepinephrine (NE) turnover, a biochemical index correlated with noradrenergic neuronal activity, was measured. The mo dification of blood pressure was also determined by telemetry during the di fferent cycles of dehydration. Dehydration caused a decrease of NE turnover in A2, A5 and A6 nuclei and in peripheral organs. The vasopressinergic lev el of dehydrated rats decreased in hypophysis and hypothalamus, and increas ed in plasma. A repeated gradual increase of arterial blood pressure during the first three days of dehydration, followed by a sudden drop when the ra ts were rehydrated on the fourth day was observed. In conclusion, our study revealed an increase in blood pressure and in central sympathetic activity during dehydration.