Renal sodium excretion following systemic infusion of vasoactive intestinal peptide in the rat

1. The aim of this clearance study was to examine the renal effects of systemic infusion of vasoactive intestinal peptide (VIP) in the intact rat. 2. Mean arterial blood pressure (MAP), plasma electrolytes and haematocrit, glomerular filtration rate (GFR), and urinary sodium and potassium excretion were measured in a baseline period and following VIP infusion (0.1-1.2 nmol/h per 200 g), as well as during a time control study. 3. During infusion of low doses of VIP (0.1 and 0.4 nmol/h per 200 g), a small increase in fractional and absolute excretion of sodium occurred but this did not differ from that occurring in the time control group. In the high dose VIP group (1.2 nmol/h per 200 g), significant falls occurred in MAP and GFR, and absolute sodium excretion fell (though not significantly) from its baseline level. 4. These findings suggest that systemic VIP has no net natriuretic effect in the rat, but produces haemodynamic changes associated with reduced sodium excretion at high doses. This study does not exclude the possibility of direct effects on tubular sodium transport of VIP released from renal nerves.