Body and Organ Weights of Rats During Acclimatization to an Altitude of 12,470 Feet

Abstract

Body and organ weights of sea level control rats were compared with those of rats (P) born at sea level and then exposed to 12,470 feet, and with those of rats (F₂) of the second filial generation born and maintained at altitude. Body weight was significantly lower from the fifth day of age in the F₂ rats than in either control or P animals. The P rats exhibited normal weight gains in the period from 1 week to 6 months at altitude; however, they showed weight loss 72 hours after reaching altitude and again after 7–10 months of exposure. Elevated hemoglobin and hematocrit values were accompanied by marked cardiac hypertrophy in all F₂ rats. In the P animals hemoglobin and hematocrit values were elevated after 2 months of exposure and reached a plateau after 6 months; moderate cardiac hypertrophy was present only after 10 months at altitude. Adrenal weight was markedly increased in all P animals but not in the F₂ rats. In the P rats at altitude for 24 and 72 hours adrenal enlargement was accompanied by thymic and lymphatic atrophy. Significant changes were not observed in the liver, kidneys, hypophysis, thyroid, testes and preputial glands.