METABOLISM OF MONOAMINES IN SPONTANEOUSLY HYPERTENSIVE RAT

Abstract

A number of reports (1) have been appeared in attempt to explain the pathogenesis of essential hypertension from the pathological, pharmacological and epidemiological points of view.
It has recently been demonstrated that norepinephrine (NE) and serotonin (5HT) are important transmitters of the nervous system. In addition, metabolic pathway of these amines has recently been clarified (2-4).
The present study is primarily concerned with a comparison between normotensive Wistar strain rats and spontaneously hypertensive rats separated from the same strain through the selective inbreedings by Okamoto and his colaborators (5). They mated Wistar strain rats which showed slightly higher blood pressure than the average under normal conditions. Continuously hypertensive first generation rats were selected and mated again in brother-sister breedings, until by serial reperation of this method, a spontaneously hypertensive colony of Wistar rats was obtained.
This hypertensive colony is useful for these experiments, because it is not so difficult to obtain numerous offsprings and they keep an average span of life, and it is not necessary to turn to any particular agent like DOCA or surgical operation to obtain hypertension. They show an almost 100% occurrence of over 150 mmHg of blood pressure after 25 weeks of age. Pathological changes (6) such as heart hypertrophy, thickening of blood vessels, and nephrosclerosis after the maintenance of hypertension being satisfactory for experimental hypertension, and it may be comparable with human essential hypertension.
The purpose of this study is to ascertain whether the metabolism of monoamines is consistently associated with hypertension or not, by means of comparison, on 5HT and NE metabolism has been made between normotensive and hypertensive rats.