Effects of different salt intakes on urinary output of catecholamines and renal sympathetic nerve activity

Abstract

To evaluate the relationship between sympathoadrenomedullary function and sodium intake, urinary output of norepinephrine (NEp), epinephrine (Ep), and dopamine (DA) and NEp turnover of kidney were measured in rats fed on high sodium (13.8 mEq/day), regular sodium (1.03 mEq/day) and low sodium (0.47 mEq/day) diet for 4 weeks. The rats with high sodium diet showed the elevation in blood pressure, pulse rate and sodium retention and augumented output of urinary NEp, Ep, and DA as compared with rats fed on regular and low sodium diets, In NEp turnover which was measured from the decreasing rate of renal NEp concentration after administration of a methyl-p-tyrosine, high sodium intake caused on enchancement of percent decrease of NEp as compared with other diets. From these resuls, it is indicated that sympathoadrenomedullary function and dopaminergic activity appears to increase with sodium loading for 4 weeks. These enchanced function and activity may participate in the increase in blood pressure and natriuresis at sodium loading.