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

We investigated the central and peripheral sympathetic responses to intermittent dehydration in rats. The norepinephrine (NE) turnover, a biochemical index correlated with noradrenergic neuronal activity, was measured. The modification of blood pressure was also determined by telemetry during the different cycles of dehydration. Dehydration caused a decrease of NE turnover in A2, A5 and A6 nuclei and in peripheral organs. The vasopressinergic level of dehydrated rats decreased in hypophysis and hypothalamus, and increased in plasma. A repeated gradual increase of arterial blood pressure during the first three days of dehydration, followed by a sudden drop when the rats 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.