Influence of dietary sodium on renin activity and arterial pressure during anesthesia

Abstract

The effect of pentobarbital anesthesia on plasma renin activity (PRA) and mean arterial pressure (MAP) was studied in chronically catheterized dogs maintained on normal or low-Na intake. Within 1 min of administration, pentobarbital caused a rapid fall in MAP which was followed by a restoration of MAP toward control within 5 min. Thirty minutes after induction of anesthesia, PRA was unchanged in Na-replete dogs and elevated 2-fold in Na-depleted dogs. MAP was significantly lowered (20 mmHg) in normal salt dogs and only slightly decreased in low-salt dogs 30 min after pentobarbital. MAP returned to preanesthetic control value in dogs given converting enzyme inhibitor before anesthesia. Surgical stress or cutaneous electrical stimulation caused a prompt rise in MAP in anesthetized dogs. This rise was blocked by hexamethonium. Change in PRA and MAP of pentobarbital-anesthetized dogs is significantly influenced by the Na intake of the animal and by the degree of surgical stress.