Effect of intermittent normoxia on muscularization of pulmonary arterioles induced by chronic hypoxia in rats.
We studied the effect of continuous and intermittent normoxia for 6 and 20 wk on the muscularization of pulmonary arterioles in rats with chronic hypoxic hypertension. After 4 wk in a hypobaric chamber (380 mm Hg) the proportion of small pulmonary blood vessels with 2 elastic laminae (PVTEL) was 21.57 +/- 14.86% (SD) (n = 10) compared with 3.66 +/- 1.86% in 10 untreated control animals. Recovery using continuous normoxia and intermittent normoxia 16 h/day for 6 wk caused a reduction in PVTEL to 8.45 +/- 4.09% (n = 6) and 7.16 +/- 6.96% (n = 6), respectively. Right ventricular hypertrophy (RVH) was reversed by recovery using continuous normoxia for 6 wk but was unaffected by intermittent normoxia (16 h/day). Intermittent normoxia 8 h/day for 6 wk did not reduce the PVTEL or RVH. Continuous normoxia for 20 wk reversed the muscularization of small pulmonary vessels (PVTEL, 3.86 +/- 3.57%; n = 4) and RVH. Intermittent normoxia (16 h/day) for 20 wk significantly diminished the PVTEL to 7.39 +/- 3.73% (n = 5) but did not reduce RVH. Prolonged continuous normoxia slowly reversed the pulmonary hypertension, RVH, pulmonary vascular lesions, and polycythemia induced by chronic hypoxia. Intermittent normoxia (16 h/day) diminished the pulmonary vascular lesions but not the pulmonary hypertension, RVH, and polycythemia. Intermittent normoxia (8 h/day) was ineffective.
D000818:Animals; D001160:Arterioles / Q000473:pathology; D001835:Body Weight; D006332:Cardiomegaly / Q000209:etiology; D005260:Female; D006976:Hypertension, Pulmonary / Q000209:etiology; D000860:Hypoxia / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D008168:Lung / Q000098:blood supply*; D009131:Muscle, Smooth, Vascular / Q000473:pathology*; D009206:Myocardium / Q000473:pathology; D009929:Organ Size; D010100:Oxygen / Q000097:blood*; D011086:Polycythemia / Q000209:etiology; D051381:Rats
D010100:Oxygen