[Hypertension in rats caused by metyrapone and heat-stress treatment]

All Wistar rats showed hypertension when they were given heat-stress and administered metyrapone (200 micrograms/kg/day), a cholesterol-11-beta-hydroxylase inhibitor. The addition of saline loading potentiated the hypertensive state. The hypertension in MH-rats was blocked by a low dose (1 mg/kg) of propranolol, a dose which was insufficient to cure the Spontanous Hypertensive rats, and by a very low dose (20 ng/kg) of 1-dopa with carbidopa treatment, but not by haloperidol, sulpiride, or prazosin. Striatal dopamine (DA) of MH-rats was increased significantly. These results suggested that the hypertension of MH-rats was related to the inhibition of central DA release. Since MH-rats showed the availability of propranolol clearly, this may be a useful model for hypertension.