P432

         Physiol Bohemoslov 1976;25(5):411-8

        Causes of experimental pulmonary hypertension in rats.

        Herget J, Paleček F, Vízek M, Holuša R.

        Experimental pulmonary hypertension was induced in young male rats by

        means of tracheoconstriction and repeated injections of aqueous bean

        (Phaseolus vulg.) extract into the trachea. After 120 days, the blood

        pressure of the experimental and control animals was measured in the

        pulmonary artery with a shaped polyethylene catheter, without opening

        the chest. In all the experimental animals the blood pressure in the

        pulmonary artery was higher than in the controls. The mean pressure in

        the pulmonary artery of the experimental rats was 25  1 torr and in

        the controls 16  0.4 torr. The right ventricle of the experimental

        animals was larger than in the controls. No difference was found between

        the systemic blood pressure values, measured in the femoral artery, in

        the experimental animals and the controls. The experimental animals had

        a faster heart rate. Cardiac output, measured by the dye dilution

        method, was the same in the control and experimental animals and there

        was likewise no difference in the PO2 PCO2 and pH values in the arterial

        blood. The inhalation of oxygen instead of air did not affect the blood

        pressure in the pulmonary artery. The pulmonary blood vessels were

        evaluated quantitatively in histological sections of the experimental

        and control animal's lungs. There was no different between the thickness

        of the media of the distal pulmonary vessels, expressed as a percentage

        of the outer diameter of the vessel, in the experimental animals and the

        controls. A media thicker than 7% was found in 15% of the evaluated

        vessels from experimental animals and in 8% of those from the controls.

        No correlation between the mean thickness of the media and the mean

        blood pressure in the pulmonary artery was found in any of the animals.