The role of adrenergic nervous system in hypertension and in the antihypertensive action of methyldopa

The role of adrenergic nervous system in hypertension and in the antihypertensive action of methyldopa was investigated. Sustained metacorticoid and renal hypertension could be produced in control and in partial immunosympathectomised (IMS) rats. Hypertension was accompanied by an elevation of aortic sodium. In total-IMS rats, metacorticoid hypertension could not be produced and renal hypertension was not sustained; the aortic sodium was not elevated. Methyldopa was effective in reducing the blood pressure in all groups (normotensive and hypertensive control and partial-IMS, and normotensive total-IMS rats) of animals. The hypotensive effect of methyldopa was not influenced by hexamethonium, phenoxybenzamine, propranolol or 3-hydroxybenzyloxyamine. It is concluded that a certain minimum level of adrenergic nervous system is essential for the induction and maintenance of experimental hypertension; and that the antihypertensive action of methyldopa is not mediated through, the adrenergic nervous system