Augmented Natriuretic Response to Infusion of Saline in Dogs Rendered Acutely Hypertensive with Metaraminol

Abstract

Summary

The mechanism of the exaggerated natriuretic response to saline infusion exhibited by hypertensive subjects is not understood. An attempt was therefore made to reproduce this phenomenon in laboratory animals rendered hypertensive by pharmacologic means. Six mongrel dogs were studied. Their natriuretic response to saline infusion at a rate of 1 ml per minute was determined. The same dogs were restudied while their blood pressure was elevated with metaraminol. An enhanced natriuretic response to normal saline infusion was observed in 5 out of the 6 dogs made acutely hypertensive with metaraminol. The demonstration that exaggerated natriuresis may be induced in a species other than man makes available an experimental model for further study of this phenomenon. The present observations support previous evidence in man that exaggerated natriuresis depends on the presence of elevated blood pressure alone and is independent of the cause of the hypertension. From the acute nature of the present experiment the thesis that exaggerated natriuresis represents the shedding of sodium sequestered during the hypertensive state is rendered untenable.