Haemodynamic changes associated with obesity and high blood pressure in rats with ventromedial hypothalamic lesions

1. The haemodynamic and plasma volume changes associated with obesity and high blood pressure were studied in nine male rats with electrolytic ventromedial hypothalamic lesions and their paired sham-operated controls. Body weight and arterial pressure were greater in the rats with ventromedial hypothalamic lesions (565 +/- 16 vs 462 +/- 14 g, P < 0.001; 128 +/- 3 vs 118 +/- 3 mmHg, P < 0.05, respectively). Cardiac output was slightly elevated, and that portion of cardiac output distributed to the kidneys was reduced (P < 0.001). Plasma volume was contracted in the rats with ventromedial hypothalamic lesions (21.0 +/- 0.1 vs 2.8 +/- 0.1 ml/100 g, P < 0.001). 2. The haemodynamic characteristics of rats in which obesity and mild hypertension have been induced by electrolytic ventromedial hypothalamic lesion are similar to mild obesity essential hypertension in men.