Effect of Hydration and Dehydration on Hypertension in the Chronic Bilaterally Nephrectomized Dog

Abstract

Fifteen dogs were bilaterally nephrectomized and maintained on a low salt diet by intermittent peritoneal dialysis for from 5-111 days. Hypertension did not develop in those dogs which became dehydrated and failed to gain in extracellular fluid vol. Hypertension did develop in those dogs which did not become dehydrated, but instead gained in wt. and extracellular fluid vol. The hypertension reached its peak in 1-2 wks. after nephrectomy. Voluntary or spontaneous dehydration of those hypertensive animals in most instances reduced the blood pressure not necessarily to a normotensive level. The dogs still remained in the hypertension category. When dehydration was too severe, shock supervened, plunging the blood pressure to a subcontrol level. Rehydration of dehydrated animals restored the blood pressure to predehydration levels or higher. A causal relationship between increase in body fluids and blood pressure is certainly suggested, but not conclusively proved. A maintained increase in body fluids is not necessary to maintain the hypertension.