Insulin-induced endothelin release and vasoreactivity in hypertriglyceridemic and hypertensive rats
Insulin-elicited endothelin release in hypertriglyceridemic, hypertensive, hyperinsulinemic (HTG) rats was shown. Weanling male Wistar rats were given 30% sucrose in their drinking water for 20–24 wk. In vitro contractions of aorta and femoral arteries were elicited with 40 mM KCl. Endothelin release induced with KCl plus 50 μU/ml insulin resulted in increases in contractile responses: 41 ± 5.9 and 57 ± 6% for control and 65.5 ± 6 and 95 ± 9% for HTG aortas and femoral arteries, respectively. The endothelin ETB-receptor blocker BQ-788 decreased responses to KCl + insulin by 39 ± 8 and 53 ± 5% in control and 48 ± 13 and 79 ± 3.5% in HTG aortas and femoral arteries, respectively. The ETA-receptor antagonist PD-151242 inhibited these responses by 12 ± 10 and 1 ± 9% in control and by 51.5 ± 9 and 58.5 ± 1% in HTG aortas and femoral arteries, respectively. These results suggest that endothelin may contribute to the hypertension in this model.