Lysosomal enzyme release from the lungs after cardiopulmonary bypass

The activity of some lysosomal enzymes has been investigated in venous and arterial blood collected from patients undergoing cardiopulmonary bypass. Before bypass, there is no arterio-venous difference in the activity of n-acetyl-beta glucosaminidase, beta-glucuronidase or lysozyme. After operation, the activity of n-acetyl-beta-glucosaminidase is greater in arterial than in superior caval blood within the first 24 h after bypass, and a small arterio-venous increment in the activity of beta-glucuronidase can also be detected towards the end of the first day. The site of enzyme release has not been identified with certainty but may lie within the pulmonary circulation.