Levels of plasma cyclic AMP and insulin in cardiac surgery

Cyclic AMP is a common second messenger for a variety of hormones such as catecholamine, glucagon, and growth hormone, which are affected by cardiac surgery. Changes in plasma cyclic AMP level may thus reflect an altered hormonal milieu. The effects of open-heart surgery on plasma cyclic AMP and its relation with serum insulin were studied in 33 adult patients who underwent cardiac surgery with cardiopulmonary bypass. Plasma cyclic AMP levels were markedly elevated during cardiopulmonary bypass and returned toward normal within several days after the operation. The serum insulin concentration remained low, and no positive correlation was found with plasma cyclic AMP level. The responses were similar in patients who had aorta-coronary bypass grafts and those who had valve replacements.