High‐dose nitroglycerin administered during rewarming preserves erythrocyte deformability in cardiac surgery with cardiopulmonary bypass.

Objective: We aimed to determine whether high‐dose nitroglycerin, a nitric oxide donor, preserves erythrocyte deformability during cardiopulmonary bypass and examines the signaling pathway of nitric oxide in erythrocytes. Methods: In a randomized and controlled fashion, forty‐two patients undergoing cardiac surgery with hypothermic cardiopulmonary bypass were allocated to high‐dose (N = 21) and low‐dose groups (N = 21). During rewarming period, patients were given intravenous nitroglycerin with an infusion rate 5 and 1 µg·kg−1·min−1 in high‐dose and low‐dose groups, respectively. Tyrosine phosphorylation level of non‐muscle myosin IIA in erythrocyte membrane was used as an index of erythrocyte deformability and analyzed using immunoblotting. Results: Tyrosine phosphorylation of non‐muscle myosin IIA was significantly enhanced after bypass in high‐dose group (3.729 ± 1.700 folds, P =.011) but not low‐dose group (1.545 ± 0.595 folds, P =.076). Phosphorylation of aquaporin 1, vasodilator‐stimulated phosphoprotein, and focal adhesion kinase in erythrocyte membrane was also upregulated in high‐dose group after bypass. Besides, plasma nitric oxide level was highly correlated with fold change of non‐muscle myosin IIA phosphorylation (Pearson's correlation coefficient.871). Conclusions: High‐dose nitroglycerin administered during cardiopulmonary bypass improves erythrocyte deformability through activating phosphorylation of aquaporin 1, vasodilator‐stimulated phosphoprotein, and focal adhesion kinase in erythrocytes. [ABSTRACT FROM AUTHOR]