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.