Cerebral regulation of renal sodium excretion in sheep infused intravenously with hypertonic NaCl.

Abstract

1. The natriuretic response to intravenous infusion of 2 M‐NaCl was investigated in six conscious sheep. This hypertonic NaCl load resulted in relatively small, physiological (2‐3 mmol l‐1) increases in plasma Na+ concentration and was followed by a natriuresis with a maximum mean urinary sodium excretion 5 times higher than pre‐infusion values. 2. Intravenous infusion of isotonic NaCl, delivering the same Na+ load as hypertonic NaCl infusion, did not induce natriuresis. This suggested, therefore, that with the hypertonic sodium load administered in the present study, the rise in plasma Na+ and/or tonicity rather than increase in blood volume is important in evoking the natriuretic response...