Effect of high and low sodium intake on norepinephrine turnover in the cardiovascular tissues and brain stem of the rabbit.

Abstract

To assess the relationship between sympathetic nerve function and sodium intake, we examined norepinephrine (NE) turnover in several cardiovascular tissues and the brain stem of rabbits maintained for 3 weeks on high (86 mEQ), normal (14 mEQ), and low (0.2 mEQ/day) sodium diet. None of the diets changed the blood pressure significantly. Plasma renin activity became high in the low sodium group and low in the high sodium group at the end of the treatment. NE turnover was measured from the rate of decline of tissue NE concentration after administration of alpha-methyl-p-tyrosine. Variation of sodium intake exerted opposite effects on NE turnover in the periphery and in the central nervous system; increasing sodium intake caused an increase in NE turnover in the thoracic aorta, mesenteric vein, and left ventricle, and a decrease in the hypothalamus, midbrain, and pons medulla. But in the mesenteric vein, and left ventricle, and a decrease in the hypothalamus, midbrain, and pons medulla. But in the mesenteric artery and abdominal aorta it was not affected by dietary sodium manipulation. The results show the varying influence of sodium balance on the central and peripheral noradrenergic neuron activity.