The contribution of the sympathetic nervous system to the development and maintenance of experimental hypertension in the rat.

1. Experimental hypertension in the rat, induced either by renal artery stenosis or by treatment with deoxycorticosterone acetate (DCA) developed maximally over a period of 8 weeks. In both types of hypertension the rate of development was unaffected by immunosympathectomy or by chemical sympathectomy following the administration of 6-hydroxydopamine.2. The effect of 6-hydroxydopamine on chronic renal hypertensive rats was to produce a hypotensive action of longer duration than when similarly administered to DCA-induced hypertensive or normotensive rats. Reserpine (5-10 mg/kg intraperitoneally) produced a more marked hypotensive effect on both types of hypertensive rats although it was of much shorter duration.3. It is concluded that experimental hypertension of renal origin or induced by DCA treatment can develop even though most of the sympathetic nervous system has been destroyed. The maintenance of chronic hypertension in these conditions may depend on the adrenal glands or a hormonal system as yet undetected.