Apoptosis of lymphocytes and sialic acid plasma level in patients undergoing cardiac surgery

Increasing evidence shows that extensive tissue trauma and surgical stress are related to physical alterations of cells and cell death. It was previously reported that total sialic acid (SA) plasma concentration is elevated in patients undergoing coronary artery surgery. Shedding or secreting of SA from the cell membrane surface or releasing intracellular SA may induce apoptosis. It is possible that the terminal SA residues of carbohydrate moieties facilitate recognition and removal of apoptotic cells by phagocytes. The aim of the present study was to estimate the dynamic changes in rate ofapoptosis oflymphocytes and total sialic acid plasma level during coronary artery surgery. In 17 patients undergoing coronary artery bypass grafting surgery plasma total SA concentration was measured and the percentage of apoptotic lymphocytes was determined before operation, after aorta clumping, after the end of operation and at 6, 18, 30 and 48 h after operation. Plasma total SA concentration decreases after aortic clumping and then increases gradually during a 48 hr observation period. The percentage of apoptotic cells increases during and after surgery with the exception of a sample taken at 18 hours after operation. The findings indicate the bimodal character of apoptosis and dynamic increase in total SA plasma level, which may be considered a result of mechanical damage taken place during operation or inflammatory response to surgical trauma.