Periventricular lesions block natriuresis to hypertonic but not isotonic NaCl loads

Abstract

The renal excretion of Na and water after an intravenous load of hypertonic or isotonic saline was studied in conscious sheep in which periventricular tissue in the region of the lamina terminalis had been ablated. Hypertonic saline (3.4-4.2 mmol/1) was infused at 0.06 mmol·kg-1·min-1 for 40 min into the jugular vein. Plasma Na concentration increased 5 mmol/1, and in normal sheep a natriuresis and increase in glomerular filtration rate ensued during the next hour. Such a natriuretic effect did not occur in sheep with periventricular lesions. By contrast, intravenous infusion of isotonic saline (30 ml/kg body wt, i.e., 0.23 mmol·kg-1·min-1 for 20 min) caused similar increase in renal Na excr..