Alteration of the Course of Hypertension in the Spontaneously Hypertensive Rat

The blood pressure of spontaneously hypertensive rats was controlled at low normotensive levels, using antihypertensive drugs for a 6-month period beginning when the rats were 3 months of age. Treatment was then withdrawn and the rats observed for an additional 4 months, until they were 13 months of age. Treatment with antihypertensive drugs arrested the progression of the hypertension and the secondary pathology for the duration of the treatment period. Following withdrawal of drugs the blood pressure did not rise to the level of the controls of a similar age, but rather it returned to the level that existed before treatment began and then progressed at the same rate that the controls exhibited when they were 3-7 months of age. Pathological changes were found only in controls. These results indicate that, although the tendency toward hypertension is inherited, its rate of development depends on environmental factors. The hypertension can be arrested by chemotherapeutic interventions and can be aggravated by excessive salt. The hypertension appears to be a progressive time-dependent process but is independent of biological processes associated with aging per se. Finally, control of blood pressure prevents end-organ damage.