title: Adaptation of the growing lung to increased Vo2: III. The effect of exposure to cold environment in rats.
abstract: This study was undertaken to further test the hypothesis that increased Vo2 operates as a stimulus for enhanced lung growth leading to a pulmonary diffusing capacity adapted to the body's O2 requirements. Vo2 was augmented by raising 4-week-old rats for 3 weeks at 11 degrees C ambient temperature, with controls kept at 24 degrees C; this led to an increase in Vo2 averaged over 24 h by 64%. In contrast to previous experiments with waltzing mice this regime did not affect body growth, as the final body weights were identical in both groups. In the cold-exposed rats the lung volume was larger by 24%, due to an increase by 26% in air volume (at about TLC), 13% in capillary blood volume and 19% in tissue volume. The alveolar and capillary surface areas were increased by 18%, and Dm and Dl by 17% and 21% respectively. It is concluded that the hypothesis of adaptation of pulmonary gas exchange capacity to increased Vo2 cannot be rejected. Whilst in previous experiments some doubts had to be retained as to the specificity of the stimulus, because of its rather marked effect on body weight, this reservation does not hold in this case. The structural modifications which lead to increased Dl in the various experimental models are discussed.
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001835:Body Weight; D003080:Cold Temperature; D008168:Lung / Q000254:growth & development*; D008176:Lung Volume Measurements; D008297:Male; D010100:Oxygen / Q000097:blood; D011650:Pulmonary Alveoli / Q000254:growth & development; D011652:Pulmonary Circulation; D011653:Pulmonary Diffusing Capacity; D051381:Rats
chemical_list: D010100:Oxygen