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

Abstract

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.

State of the art in fluid and volume therapy

“…It is important to realize that the blood volume can only increase slightly due to infusions [24]. ANP is released immediately, the vascular barrier becomes permeable, and the blood volume quickly returns to normal high [25][26][27]74]. In the case of larger blood losses, a moderate -sometimes considerable, as demonstrated by the presented example -hypovolemia is much more frequent, caused by an apparently generous but in fact inadequate volume therapy.…”

“…Volume loading is associated with small volume effects, but also with adverse events [24]. This owes to the fact that volume loading (infusion in the absence of corresponding fluid loss) causes expansion of the atria and thus release of atrial natriuretic peptide (ANP) [25][26][27]. This peptide alters the endothelial glycocalyx, thus, increasing extravasation of macromolecules (colloids) and fluid.…”

Vascular Endothelial Dysfunction during Cardiac Surgery: On-Pump versus Off-Pump Coronary Surgery

“…The results presented in this report originate from a comprehensive study investigating the association of release of atrial natriuretic peptide with shedding of 3 components of the EG during on- as opposed to off-pump coronary artery surgery [13]. However, the aforementioned study focused on damage to the EG and does not contain data on liberation of Ang-1, Ang-2, VE-cadherin, or endocan in this setting.…”

The Physiology of Volume Resuscitation

“…Natriuretic peptides cleave membrane-bound proteoglycans and glycoproteins (most notably syndecan-1 and hyaluronic acid) off the endothelial glycocalyx [42][43][44]. The glycocalyx plays a major role in determining the vascular barrier function, preventing large macromolecules and fluid moving across the endothelium.…”