title: Probable strain differences of rats in susceptibilities and cardiopulmonary responses to chronic hypoxia.
abstract: Susceptibility to chronic hypoxia in the form of simulated high altitude (HA) have been compared in the adult male Hilltop (H) and Madison (M) Sprague-Dawley rats in terms of their metabolic, hematological and cardiopulmonary responses. Following exposure to either 18 000 or 20 000 ft for 30-40 days, 60-70% of the H rats died or became obviously morbid in contrast to a total absence of morbidity or mortality in the M rats. Autopsy of dead and morbid H rats revealed abdominal and pleural effusions. Oxygen consumption remained normal in both H and M rats. Hematocrits were slightly higher in the H rats than in the M rats. The lungs of both strains were hypertrophied but they showed no evidence of edema or gross lesions. The peak right ventricular pressures of the H and M strains were 73.6 +/- 7.4 and 49.5 +/- 6.5 mm Hg (mean +/- SD), respectively. The percent increase in total ventricular, right and left ventricular weights per 100 g body weights in the H rats were 80, 300 and 30, respectively, as compared to 20, 200 and 0 in the M rats. These changes suggest that the greater susceptibility to chronic HA exposure observed in the H rats is related to a more severe right ventricular overloading and perhaps failure, secondary to a more extreme pulmonary hypertension.
mesh_terms: D000531:Altitude; D000818:Animals; D006332:Cardiomegaly / Q000209:etiology; D002908:Chronic Disease; D004198:Disease Susceptibility; D006321:Heart / Q000503:physiopathology*; D006984:Hypertrophy / Q000209:etiology; D000860:Hypoxia / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D008168:Lung / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains / Q000254:growth & development / Q000502:physiology*