Nitrendipine attenuates the pulmonary vascular remodeling and right ventricular hypertrophy caused by intermittent hypoxia in rats.

We designed experiments to determine whether intermittent hypoxia would produce significant pathologic and physiologic changes in rats and whether pretreatment with a calcium channel blocker, nitrendipine, would reduce the pulmonary vascular remodeling and right ventricular hypertrophy caused by intermittent hypoxia. Intermittent exposure to hypobaric hypoxia (0.5 atmospheres) 10 h a day for 30 days increased the hematocrit (65 ± 1 versus 42 ± 1%, mean ± SEM), right ventricular systolic pressure (33 ± 1 versus 20 ± 1 mmHg), and right ventricular weight adjusted for body weight (RV/BW) (126 ± 6 versus 60 ± 2 mg/100 g) in male Sprague-Dawley rats. Intermittent hypoxia also increased the percentage of small pulmonary vessels with muscle (76 ± 3 versus 19 ± 5%) and the thickness of the vessel wall as a percentage of the total vessel diameter (34 ± 1 versus 22 ± 1%). Nitrendipine (10 mg/kg) prevented the acute increase in right ventricular systolic pressure caused by hypoxia. Chronic treatment with nitrendipin...