Release of atrial natriuretic peptide precedes shedding of the endothelial glycocalyx equally in patients undergoing on- and off-pump coronary artery bypass surgery

The present study investigates why shedding of the endothelial glycocalyx occurs both in patients undergoing on- and off-pump coronary artery bypass surgery. Release of atrial natriuretic peptide (ANP) was of special interest, because ANP initiates shedding ex vivo. Three major constituents of the glycocalyx (syndecan-1, heparan sulfate and hyaluronan) were measured in arterial blood of patients undergoing coronary artery bypass surgery with (n = 15) and without (n = 15) cardiopulmonary bypass at various phases of the procedure. Additionally, the levels of the inflammatory cytokines interleukin (IL)-6, -8, and -10 and of ANP were evaluated. Elevations of all three components of the glycocalyx were detected in blood of patients undergoing on- (maximum increases: syndecan-1 15-fold, heparan sulfate ninefold, hyaluronan fivefold basal) and off-pump (maximum increases: syndecan-1 fourfold, heparan sulfate twofold, hyaluronan threefold basal) coronary artery surgery. Maximum ANP concentrations increased three- and fourfold basal in on- and off-pump coronary artery surgery, respectively (P < 0.05). There were significant increases in the three cytokine concentrations in both on- (maximum increases: IL-6 146-fold, IL-8 23-fold, IL-10 238-fold basal) and off-pump (maximum increases: IL-6 77-fold, IL-8 eightfold, IL-10 58-fold basal) coronary artery surgery. However, the elevations of ANP preceded those of the cytokines and coincided with or even preceded shedding of the human endothelial glycocalyx in both surgical procedures. These data suggest that release of ANP may lead to perturbation of the endothelial glycocalyx in both on- and off-pump coronary artery bypass surgery.