AJP - Heart and Circulatory Physiology, Vol 243, Issue 2 328-H339, Copyright © 1982 by American Physiological Society
Postnatal carbon monoxide exposure: immediate and lasting effects in the rat
D. G. Penney, M. S. Baylerian, J. E. Thill, C. M. Fanning and S. Yedavally
Groups of newborn rats inhaled 500 ppm CO for 32 days, after which they
continued development in ambient air. The ratio 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. At 14 days of age, the weight of the left ventricle plus
interventricular septum (LV + S) exceeded the controls by 80%, whereas the
weight of the right ventricle (RV) was 100% greater. RV weight remained
significantly greater than that of the controls at 68, 107, and 217 days of
age. The ratio of RV weight to LV + S weight remained higher than that of
the controls both during and after CO exposure. Myocardial deoxyribonucleic
acid (DNA) concentration (microgram/mg dry wt) declined more rapidly in the
CO-exposed groups during the first 2 wk. DNA content (microgram/LV + S +
RV) was not significantly different. There were no differences in DNA
concentration or content after CO exposure. Hydroxyproline, used as an
index of collagen content, was unaffected by postnatal cardiomegaly.
Hydroxyproline concentration was depressed only during the first 3 wk.
Cardiac cytochrome c concentration was depressed and lactate dehydrogenase
M subunit composition elevated only during CO exposure. Neither lactate
dehydrogenase specific activity nor myoglobin concentration was altered
during or after CO treatment. Neither the DNA nor hydroxyproline data
provide an explanation for "persistent cardiomegaly."
