Brain tyrosine hydroxylase activity and systolic blood pressure in rats treated with either deoxycorticosterone and salt or angiotensin.

The hypertension induced in adult male rats by doca/salt was found to be accompanied by a significant rise in whole brain tyrosine hydroxylase (TH) activity. A smaller hypertensive effect, produced by angiotensin (750 ng kg-1 daily) was also accompanied by a proportional rise in whole brain TH activity. The specific antagonists spironolactone and saralasin completely blocked both responses in the doca/salt- and angiotensin-treated animals respectively and spironolactone showed a partial inhibition of the effects of angiotensin. In all the animals treated there was a clear correlation between systolic blood pressure and whole brain TH activity. The significance of these changes is discussed in the light of the central mechanism of hypertension.