Role of arterial wall secretion in the regulation of blood pressure.

The authors present experiments demonstrating that the hypertension produced by the stimulation of the central end of the vagus nerve is brought about by the appearance of a pressor substance in the circulating blood. The results of these experiments show that such a substance does not come from any gland nor from the central nervous system. The observed facts indicate that its origin is the arterial wall proper, from which it is directly liberated into the circulation. The pharmacologic proofs suggest that this substance is noradrenaline. IN 1947 we showed' that electric stimulation of the central ends of the cut vagus nerves produces a vasopressor response accompanied by release of a vasoconstrictor substance which we believed came from arterial walls. We showed subsequently2,34, 5 that this vasoconstrictor substance does not come from an endocrine organ, and have reported our views on its origin and nature.6 This report reviews and extends these observations. METHODS Mongrel dogs were anesthetized with sodium pentobarbital (32 mg. per kilogram). Blood pressures were recorded on a smoked drum from a can-nulated femoral artery connected to a mercury manometer. The vagus nerves were isolated in the neck and cut between ligatures; their central ends were stimulated by applying a silver electrode connected to an inductor. Duration of stimuli was between 10 and 60 seconds at a frequency of 20 to 50 cycles per second with a pulse duration of 3 to 8 milliseconds.