Hypothalamic Tonic Regulation of Blood Pressure in Spontaneously Hypertensive Rats

Separation of the neural connection between posterior hypothalamus and mesencephalon with a special knife elicited abruptly a slight but prolonged fall in blood pressure in normotensive Wistar rats (-18±5 mmHg), while other separations in the hypothalamus or between hypothalamus and other brain structures were ineffective. This fall of blood pressure was significantly greater in Spontaneously Hypertensive Rats (-34±11 mmHg). These facts favoured the evidence of hypothalamic tonic influence to blood pressure regulation and its participation in the pathogenesis of the spontaneous hypertension.