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Open Access Highly Accessed Research

Effects of endotoxin on lactate metabolism in humans

Burkhard Michaeli1, Alexandre Martinez1, Jean-Pierre Revelly1, Marie-Christine Cayeux1, René L Chioléro1, Luc Tappy2 and Mette M Berger1*

Author Affiliations

1 Service of Adult Intensive Care, Lausanne University Hospital (CHUV), Rue du Bugnon 46, Lausanne 1011, Switzerland

2 Department of Physiology, University of Lausanne, School of Biology and Medicine, Rue du Bugnon 7, Lausanne 1011, Switzerland

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Critical Care 2012, 16:R139  doi:10.1186/cc11444


See related commentary by Gibot, http://ccforum.com/content/16/5/151

Published: 27 July 2012

Abstract

Introduction

Hyperlactatemia represents one prominent component of the metabolic response to sepsis. In critically ill patients, hyperlactatemia is related to the severity of the underlying condition. Both an increased production and a decreased utilization and clearance might be involved in this process, but their relative contribution remains unknown. The present study aimed at assessing systemic and muscle lactate production and systemic lactate clearance in healthy human volunteers, using intravenous endotoxin (LPS) challenge.

Methods

Fourteen healthy male volunteers were enrolled in 2 consecutive studies (n = 6 in trial 1 and n = 8 in trial 2). Each subject took part in one of two investigation days (LPS-day with endotoxin injection and placebo-day with saline injection) separated by one week at least and in a random order. In trial 1, their muscle lactate metabolism was monitored using microdialysis. In trial 2, their systemic lactate metabolism was monitored by means of a constant infusion of exogenous lactate. Energy metabolism was monitored by indirect calorimetry and glucose kinetics was measured with 6,6-H2 glucose.

Results

In both trials, LPS increased energy expenditure (p = 0.011), lipid oxidation (p<0.0001), and plasma lactate concentration (p = 0.016). In trial 1, lactate concentration in the muscle microdialysate was higher than in blood, indicating lactate production by muscles. This was, however, similar with and without LPS. In trial 2, calculated systemic lactate production increased after LPS (p = 0.031), while lactate clearance remained unchanged.

Conclusions

LPS administration increases lactatemia by increasing lactate production rather than by decreasing lactate clearance. Muscle is, however, unlikely to be a major contributor to this increase in lactate production.

Trial registration

ClinicalTrials.gov NCT01647997