Role of Autonomic Nervous System in Maintenance of Cerebral and Renal Hypertension

The blood pressure responses to various drugs were investigated in renal hypertensive, cerebral hypertensive and normotensive rabbits. Hexamethonium bromide and Dibenamine reduced the blood pressures of renal and cerebral hypertensives. Effects in the normal were insignificant. The cerebral hypertensive's blood pressure was slightly affected by benzodioxane. Blood pressure was not reduced at all in the other groups. Blood pressure of the renal hypertensive rabbit was greatly reduced by Veriloid and dihydroergocornine. Blood pressures of cerebral and normal animals were affected to a lesser degree. The results suggest that maintenance of hypertension in the cerebral hypertensive rabbit depends on an overactive sympathetic nervous system, possibly due to the release of medullary pressor centers from inhibitory impulses originating in higher centers; whereas, the maintenance of hypertension in the renal hypertensive rabbit may be attributed to an increased reactivity of the peripheral vasculature to a normal sympathetic tone.