Effects of verapamil and aspirin on experimental chronic hypoxic pulmonary hypertension and right ventricular hypertrophy in rats.

Rats made hypoxic by confinement in hypoxic cages for 4 weeks developed pulmonary hypertension and right ventricular hypertrophy. Treatment with Verapamil or aspirin reduced both chronic hypoxic pulmonary hypertension and the hypertrophy of the right ventricle. The antihypertensive effect of Verapamil is explained by the involvement of the transmembrane calcium flux in pulmonary vascular smooth muscle in the hypoxic vasoconstrictory response. Part of the antihypertensive effect of inhibition of prostaglandin synthesis is attributed to a decrease in packed cell volume produced in hypoxic, aspirin treated rats.