Vasopressin Aggravates Cardiopulmonary Bypass-Induced Gastric Mucosal Ischemia

Background/Aim: Upper gastrointestinal bleeding (UGIB) is one of the most frequent gastrointestinal complications after cardiac surgery with cardiopulmonary bypass (CPB). Endothelin expression and microcirculatory dysfunction have been shown to be involved in UGIB. The aim of this study was to analyze the effect of vasopressin during CPB on the gastric mucosal microcirculation and the involvement of the endothelin system. Methods: Eighteen pigs were randomized into three groups (n = 6 each): group I = sham, group II = CPB (1-hour CPB) and group III = CPB + vasopressin (1-hour CPB and vasopressin administration during CPB to maintain baseline arterial pressure). All animals were observed for a further 90 min after termination of CPB. Systemic hemodynamics as well as blood flow and oxygen saturation of the gastric mucosa were measured continuously. At the end of the experiment, the gastric mucosal expressions of endothelin-1 (ET-1) and its receptor subtypes A (ETA) and B (ETB) were determined by polymerase chain reaction. Gastric mucosal injury, apoptotic cell death and leukocytic infiltration were determined by histology and immunohistochemical analyses of cleaved caspase-3 and myeloperoxidase. Results: CPB decreased gastric microvascular perfusion, which was associated with an increased expression of ET-1 and ETA. Vasopressin aggravated the CPB-associated malperfusion, whereas it completely abrogated the upregulation of ET-1 and ETA. Interestingly, vasopressin did not induce gastric mucosal morphologic injury, leukocytic infiltration or apoptotic cell death. Conclusion: Vasopressin aggravates CPB-associated microvascular malperfusion of the gastric mucosa but does not induce gastric mucosal injury.