Modulation of mesenteric vasoreactivity and inflammatory response by protein undernutrition in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is responsible for an inflammatory response that can lead to postoperative organ dysfunction. Undernutrition increases the risk of organ failure. We investigated the effect of undernutrition on the inflammatory response and mesenteric vascular reactivity induced by CPB in rats.

CPB was performed in Wistar rats given normal nutrition or protein undernutrition. Mesenteric artery contractility was determined in the presence of increasing concentrations of phenylephrine with or without nitric oxide synthase blockade. Relaxation was assessed in the presence of acetylcholine or sodium nitroprusside. The inflammatory response was evaluated by the measurement of systemic tumor necrosis factor-α at cannulation and after 150 min and by a histologic study of pulmonary and gut leukocyte infiltration.

CPB and protein undernutrition induced hypercontractility to phenylephrine and early relaxation defects in the mesenteric arteries. CPB caused endothelial dysfunction with early impairment of endothelium-dependent relaxation. Protein undernutrition led to an impaired relaxation of the mesenteric arteries, which was in part endothelium independent. Concomitantly, a significant inflammatory response was observed.

CPB and undernutrition induce mesenteric hypercontractility to α1-adrenergics and impair vascular relaxation, without any additive effect of CPB on undernutrition. Undernutrition causes inflammation and a lack of vascular relaxation, probably involving smooth muscle contractile mechanisms.