Alterations in type II pneumocytes cultured after partial pneumonectomy.

Type II pulmonary epithelial cells prepared from the lungs of normal rats were compared in primary culture to cells derived from the right lung of animals subjected previously to left pneumonectomy (PNX). Studies were initiated on the sixth post-PNX day, during the rapid phase of compensatory right lung growth. After 24 h in vitro, PNX cells were 30-40% larger than controls and contained 20-50% more DNA. The magnitude of these differences was dependent on serum concentration (fetal calf serum; 1 and 10%, respectively) and, under most conditions, decreased as culture time was extended to 48 or 72 h. Incorporation of [3H]thymidine into DNA was also elevated (greater than 50%) on the first culture day in the PNX group at both serum levels, and remained so through day 3 at low serum, as thymidine incorporation became more rapid in all cells. Similarly, rates of spermidine uptake were elevated in cells prepared from lungs of PNX animals on culture day 1, but this effect too was lost by day 3. Thus type II pneumocytes isolated from the lungs of PNX rats exhibit metabolic changes typical of accelerated cell growth at early intervals of primary culture in vitro. Although these changes are lost as culture time is extended and the cells lose differentiated characteristics, the results suggest that such pneumocytes may provide useful information regarding factors which regulate compensatory growth of lung tissue.