Comparison of Norepinephrine Release in Hypertensive Rats: I Hypothalamic and Brainstem Tissues

Abstract

Stimulation induced ³H-norepinephrine release was measured in hypothalamus and brainstem of spontaneously hypertensive (SHR) and normotensive (WKY) rats. Age dependent changes in ³H-norepinephrine release were shown to occur in the anterior and posterior hypothalamus and the A₂ region of the nucleus tractus solitarius (NTS). In an attempt to determine whether these changes in ³H-trasmitter release were causal or merely secondary to the increase in blood pressure, similar release studies were carried out in DOCA-salt and one kidney-one clip hypertensive animals with similar levels of systolic blood pressure. The changes in stimulus-induced ³H-norepinephrine release seen in the SHR were not observed in the other two models of hypertension, suggesting that one: they were not secondary to an increase in systolic blood pressure; and two that the changes observed in the SHR may possibly play a role in the development and/or maintenance of the hypertension.