[Verapamil and nifedipine limit hemodynamic changes in pulmonary circulation in rats with hypoxia]

The effect of hypobaric hypoxia on right ventricular pressure, right ventricular mass and hematocrit was assessed in Wistar rats divided into 4 groups. Group I comprised 20 control animals, kept in normal conditions. Groups II, III and IV consisted of 34-40 rats each at the beginning of the experiment. The animals were exposed to intermittent hypobaric hypoxia (380 mmHg, 10-12% O2, temperature 22 degrees C) 8 hours a day, 6 days a week, for 5 consecutive weeks. In group II no medication was given, in group III verapamil (Isoptin-Knoll) was administered in the drinking water at 30 mg/kg body mass/day, and in group IV nifedipine (Corotrend--Siegfried) was applied at 6 mg/kg body mass/day. Control animals were injected with i.p. nembutal (35 mg/kg) and then a polyethylene cannula was inserted in the right ventricle via external jugular vein, with consecutive measurement of right ventricular pressure. Hematocrit was measured in the arterial blood. After the animals had been sacrificed, the heart was isolated, right ventricle was excised and its mass was assessed as the ratio to mass of left ventricle-interventricular septum block. In groups II, III and IV right ventricular pressures were measured on days 10, 20 and 30 of the exposure to hypoxia. The hematocrit and ventricular mass were obtained at termination of the experiment. In the control group, mean right ventricular pressure was 28.5 +/- 3.5 mmHg, hematocrit 43.4 +/- 1.75% and right/left ventricular mass ratio was 0.267 +/- 0.03.(ABSTRACT TRUNCATED AT 250 WORDS)