Noradrenaline concentration and turnover in nuclei of the hypothalamus and the medulla oblongata at two stages in the development of renal hypertension in the rat

Abstract

The noradrenaline concentration and the α-methyl-para-tyrosine (α-MPT)-induced disappearance of noradrenaline were determined in several nuclei of the hypothalamus and the medulla oblongata of renal hypertensive rats (two-kidney Goldblatt hypertension). A decreased α-MPT-induced disappearance of noradrenaline was found in the nucleus interstitialis striae terminals and nucleus paraventricularis 3 days after renal artery constriction, when blood pressure was slightly, but significantly higher than that of sham operated rats. At this stage the α-MPT-induced disappearance of noradrenaline was enhanced in the nucleus commissuralis and the A1 of hypertensive rats while the noradrenaline concentration in the A1-region was significantly elevated. No significant differences were found in both parameters in hypothalamic and medullary nuclei 3.5 weeks after the operation, when hypertension had fully developed. These findings are indicative of the occurence of transient changes in the activity of noradrenergic neurons located in the medulla oblongata and projecting to the hypothalamus during the initiation of the development of two-kidney Goldblatt hypertension.