L-Laktat und H2O2-Bestimmungen im Atemkondensat unter Ruhebedingungen sowie unter leichter bis mittelgradiger Belastung von jungen gesunden Probanden

Abstract

The recently developed microenzyme detectors make a non-invasive measurement of inflammatory markers and L-lactate in exhaled breath condensate (EBC) possible. In a group of young and healthy subjects, we examined whether L-lactate and H (2)O (2) can be detected in EBC. During resting conditions as well as at 60 and 120 Watt external load on a cycle ergospirometer 100 l exhaled air were collected under stationary load conditions from 19 healthy subjects. Exhaled breath condensate (EBC) was obtained by cooling the expired air volume. The analysis was performed within 90 min using an ECo-Check amperometer (Viasys Health Care). The H (2)O (2) measurement was performed amperometrically by means of a biosensor after chemical reaction catalysed by peroxidase. Lactate measurements were performed using a bienzyme sensor after lactate oxidase-induced oxidation of L-lactate to pyruvate and H (2)O (2). The rates of release of L-lactate in nmol/min und H (2)O (2) in pmol/min were calculated from the concentrations of L-lactate and H (2)O (2) in the EBC and the time of collection. At rest 100 l exhaled air were collected in 10.6 +/- 5.1 min, and 0.99 +/- 0.3 ml EBC were obtained, at the 60 Watt step 1.23 +/- 0.47 ml EBC were collected in 6.7 +/- 1.8 min, and at 120 Watt 1.09 +/- 0.38 ml EBC in 4.8 +/- 0.8 min. At rest, there was a mean rate of L-lactate release of 3.3 +/- 3.1 nmol/min, which increased at the 60 Watt step to 8.4 +/- 5.1 nmol/min (p < 0.05), and at 120 Watt to 5.0 +/- 12.6 nmol/min (p < 0.02). The rate of L-lactate was proportional to the metabolic rate (r = 0.99). The rate of H (2)O (2) release at rest was 49.1 +/- 37.9 pmol/min, it increased at 60 Watt to 159 +/- 113 pmol/min (p < 0.05) and decreased at 120 Watt to 96.5 +/- 49.5 pmol/min (p < 0.05). Significant measurable concentrations of L-lactate and H (2)O (2) in the exhaled breath condensate were found already under resting conditions. During external load, an increase in the L-lactate concentration was found, correlating with the metabolic rate. H (2)O (2) is an inflammatory marker, its concentration in the EBC was markedly increased during the first step of applied external load, but less during the second. A probable correlation between L-lactate concentration in EBC and arterialized blood will be studied in future investigations.