Effect of cardiopulmonary bypass on the circulating level of soluble GMP-140.

Soluble GMP-140 can prevent the adhesion of activated neutrophils to endothelium in vitro. Because cardiopulmonary bypass causes neutrophil-endothelial interaction, the plasma level of soluble GMP-140 was measured using an enzyme immunoassay system in 32 children undergoing intracardiac repair of congenital heart disease. They had either a high, low, or normal pulmonary blood flow (n = 13, 12, and 7 respectively). Because activated platelets are a source of GMP-140, the plasma beta-thromboglobulin level was also measured. Blood was sampled before, during, and for 24 hours after cardiopulmonary bypass. Plasma levels of both soluble GMP-140 and beta-thromboglobulin increased after the onset of cardiopulmonary bypass in all patients but for both substances the increase was greater in those with a low pulmonary blood flow (p < 0.05 for all comparisons). The sum total of soluble GMP-140 values during and after operation was correlated negatively with the preoperative mean pulmonary arterial pressure (p < 0.05 for all time intervals). GMP-140 level correlated with the plasma beta-thromboglobulin level (r = 0.5, p < 0.05). This work supports the contention that soluble GMP-140 is released from activated platelets during cardiopulmonary bypass, the level being particularly high in those who had intrinsically abnormal platelets preoperatively in association with a low pulmonary blood flow. Patients with a high pulmonary blood flow, who are more susceptible to endothelial cell injury, may be less well protected by soluble GMP-140.