Effects of selective iNOS inhibition on gut and liver O2-exchange and energy metabolism during hyperdynamic porcine endotoxemia.

Abstract

We have previously demonstrated that non-selective nitric oxide synthase (NOS) inhibition did not reverse the LPS-induced deterioration of hepato-splanchnic energy status in porcine endotoxic shock. Therefore, this study investigated the effect of selective inducible NOS (iNOS) inhibition using 1400 W on intestinal and liver perfusion, O2 kinetics, and energy metabolism during hyperdynamic porcine endotoxemia. Intravenous E. Coli LPS was continuously infused over 24 h concomitant with fluid resuscitation. After 12 h of endotoxemia, continuous intravenous infusion of 1400 W was started until the end of the experiment and was titrated to maintain mean blood pressure (MAP) at baseline levels. Twelve, 18, and 24 h after starting LPS, we measured hepatic arterial and portal venous blood flow, ileal mucosal-arterial PCO2 gap, portal as well as hepatic venous lactate/pyruvate ratios, and endogenous glucose production rate. Expired NO and plasma nitrate levels were assessed as a measure of NO production. 1400 W decreased LPS-induced increase in expired NO and allowed for the maintenance of MAP without modification of cardiac output. Despite unchanged regional macrocirculation, 1400 W prevented the progressive rise of ileal mucosal-arterial PCO2 gap, significantly improved the LPS-induced impairment of hepato-splanchnic redox state, and blunted the decline in liver lactate clearance. Increased glucose production rate was not influenced. Thus, the selective iNOS inhibition with 1400 W prevented circulatory failure and largely attenuated otherwise progressive LPS-induced deterioration of intestinal and hepatocellular energy metabolism.