The effect of cardiopulmonary bypass on the expression of inducible nitric oxide synthase, endothelial nitric oxide synthase, and vascular endothelial growth factor in the internal mammary artery.

Objective: Endothelial function of a vessel may be impaired by local or systemic inflammation initiated by cardiopulmonary bypass (CPB) during coronary artery bypass graft (CABG) surgery. The present study was designed to investigate the early effects of CPB on nitric oxide production and vascular endothelial growth factor (VEGF) expression in internal mammary artery (IMA).

Design: Prospective study.

Setting: University hospital.

Participants: Twenty patients who were scheduled for elective CABG with CPB.

Interventions: IMA sections were studied immunohistochemically from these patients. The samples were taken from the distal end of the IMA before the institution of CPB and just before the construction of the IMA-left anterior descending artery anastomosis.

Measurement And Main Results: After CPB, VEGF and endothelial nitric oxide synthase immunoreactivity increased significantly when compared with baseline values in the endothelium (p = 0.0156, p = 0.0313) and adventitia (p = 0.0313, p = 0.0001), respectively. No significant change was observed in inducible nitric oxide synthase immunoreactivity.

Conclusions: The increase in eNOS expression may have been induced by the inflammation caused by CPB.