Alterations in enzymes related to adenosine 3',5'-monophosphate during compensatory growth of rat lung.

Left pneumonectomy in rats induced growth of the right lung which was maximum one week after the operation. This compensatory lung growth was accompanied by an increase in adenylate cyclase/cyclic AMP phosphodiesterase activity suggesting an increase in the lung adenosine 3',5'-monophosphate (cyclic AMP) levels after pneumonectomy. Activities of cyclic-AMP-dependent protein kinase, phosphorylase and glucose 6-phosphatase were also increased suggesting the enhanced activity of the cascade system (glycogenolysis). Activities of these enzymes were maximally elevated during the first three days of operation and preceded the growth of contralateral lung, returning to the presurgery level on day 14. These data indicate that: (a) the biochemical response to pneumonectomy in rats appeared to be complete in two weeks and, (b) changes in the activities of cyclic-AMP-related enzymes may be important in the compensatory growth of rat lung.