Postnatal carbon monoxide exposure: Immediate and lasting effects in the rat

Groups os newborn rats inhaled 500 ppm CO for 32 days, after which they continued development in ambient air. The ration of heart weight to body weight increased sharply after birth, peaked at 14 days of age, and then fell progressively but remained above that of normal rats at 68 and 107 days of age. Myocardial deoxyribonucleic acid (DNA) concentration ( mu g/mg dry wt) declined more rapidly in the CO-exposed groups during the first 2 wk. DNA content ( mu g/LV + S + RV) was not significantly different. There were no differences in DNA concentration or content after CO exposure. Neither the DNA nor hydroxyproline data provide an explanation for "persistent cardiomegaly."