Hemodynamic effects of vanadate administration in rats with different levels of sodium intake

The acute hemodynamic effect of an intravenous (IV) bolus of vanadate (10 mumol/kg bwt) followed by an IV infusion at 0.5 mumol/kg min was studied in Wistar rats at three different levels of Na intake: low Na+ (0.5 mEq/24 h), normal Na+ (1.5 mEq/24 h), and high Na+ (15 mEq/24 h). Hemodynamic changes were measured using the radioactive microsphere method. Vanadate decreased cardiac output by 52.0 +/- 6.4% in low Na+ rats, by 41.2 +/- 3.3% in normal Na+, and by 29.2 +/- 3.1% in high Na+ group. Total peripheral resistances increased by 47.1 +/- 26% in high Na+ rats, by 80.1 +/- 6.6% in normal Na+, and by 96.3 +/- 4.5% in low Na+ group. Renal blood flow decreased by 70 +/- 4% in low Na+, 58 +/- 3% in normal Na+, and 39 +/- 3% in high Na+. Cerebral, testicular, and splanchnic blood flow showed smaller changes. These results demonstrate that intravenous vanadate induces marked hemodynamic changes that depend on Na+ intake being more striking when the intake of sodium is reduced.