Role of cyclic AMP in proliferation of lung tissue in organ culture.

The role of cyclic AMP in cell proliferation and division has been the subject of study by a number of investigators in the past 30 years, but the argument of whether cyclic AMP is a negative or a positive regulator has not been settled. We studied the effect of cyclic AMP on proliferation of normal and postpneumonectomized lung tissues in young adult rats by measuring the incorporation of tritiated thymidine into lung DNA in organ culture. In normal lung tissues the incorporation of [3H]thymidine was increased by exogenous dibutyryl cyclic AMP, or by isoproterenol or forskolin to stimulate adenylate cyclase, or by caffeine, which inhibits cAMP phosphodiesterase.

Role of hyperventilation in hypoxia on lung growth in rats.

This study was conducted in an attempt to differentiate the contribution of hyperventilation, if any, from that of low PO2 on adaptive lung growth in response to hypoxia. Male albino rats were exposed to one of the following: (1) Room air for 7 days, as control; (2) 10% O2 in N2 for 7 days; (3) 10% O2 for 6 h, 1 day or 2 days and air for the remaining of 7 days; (4) 10% O2 for 2 days and 7% CO2 in air for 5 days; (5) air for 2 days and 7% CO2 for 5 days; or (6) 7% CO2 in air for 7 days. Lung growth was assessed by measuring the lung weight, lung air volume, lung DNA content and rate of DNA synthesis in lung explants.

Fetal lung growth: influence of maternal exposure to cold and exercise in rats.

The consequences of maternal exposure to low ambient temperature and exercise on maternal and fetal lung growth and in particular on the relationship between the three gas exchange organs (lungs and placenta) were studied in albino rats. Pregnant rats were subjected to 10 degrees C ambient temperature or to daily 10 min swimming exercise beginning at day 3 or day 11 of pregnancy till day 21 when they were sacrificed. Maternal lung growth was assessed by measuring the lung weight, lung air volume and lung DNA content, and the fetal lung growth by lung DNA content.

Fetal lung growth: influence of maternal hypoxia and hyperoxia in rats.

The consequences of maternal hypoxia and hyperoxia on maternal and fetal lung growth and in particular on the relationship between the three gas exchange organs (lungs and placenta) were studied in albino rats. Pregnant rats were exposed to one of the following: (1) 10% O2 in N2 or 100% O2 for 2 days beginning at day 7, 11, 14, or 18 of pregnancy; (2) 10% O2 in N2 or 100% O2 for 10 h/day beginning at day 7; or (3) 14-11% O2 in N2 continuously beginning at day 14 till day 21 when they were sacrificed. Maternal lung growth was assessed by measuring the lung weight, lung air volume and lung DNA content, and the fetal lung growth by lung DNA content.

Influence of maternal pneumonectomy on fetal lung growth.

This study was conducted to test the hypothesis that the compensatory growth of the maternal lung during pregnancy influences fetal lung growth, specifically the fetal lung DNA content. A left pneumonectomy (PN) was performed in pregnant albino rats at different gestation days (GD 3, 7, 9, 10, 12, 14, 16 and 18) and the rats sacrificed at GD 21. Only mothers with litter size of 9-14 fetuses were used for this study.