Measurements of lactate in exhaled breath condensate at rest and after maximal exercise in young and healthy subjects

Abstract

Arterial lactate concentrations, taken as indicators of physical fitness, in athletes as well as in patients with cardio-respiratory or metabolic diseases, are measured invasively from arterialized ear lobe blood. Currently developed micro enzyme detectors permit a non-invasive measurement of hypoxia-related metabolites such as lactate in exhaled breath condensate (EBC). The aim of our study is to prove whether this technology will replace the traditional measurement of lactate in arterialized blood. Therefore, we determined the functional relation between lactate release in EBC and lactate concentration in blood in young and healthy subjects at rest and after exhausting bicycle exercise. During resting conditions as well as after exhausting bicycle exercise, 100 L of exhaled air along with blood samples from the ear lobe was collected after stationary load conditions in 16 healthy subjects. EBC was obtained by cooling the expired air volume with an ECoScreen I (FILT GmbH, Berlin) condenser. The analysis was performed within 90 min using an ECoCheck ampere meter (FILT GmbH, Berlin). Lactate measurements were performed using a bi-enzyme sensor after lactate oxidase-induced oxidation of lactate to pyruvate and H2O2. The rates of lactate release via the exhaled air were calculated from the lactate concentration, the volume and the collection time of the EBC. The functional relation of lactate release in exhaled air and lactate concentration of arterial blood was computed. At rest, the mean lactate concentration in arterialized blood was 0.93 ± 0.30 mmol L(-1). At a resting ventilation of 11.5 ± 3.4 L min(-1), the collection time for 100 L of exhaled air, Ts, was 8.4 ± 2.9 min, and 1.68 ± 0.40 mL EBC was obtained. In EBC, the lactate concentration was 21.4 ± 7.7 µmol L(-1), and the rate of lactate release rate in collected EBC was 4.5 ± 1.7 nmol min(-1). After maximal exercise load (220 ± 20 W), the blood lactate concentration increased to 10.9 ± 1.8 mmol L(-1) and the ventilation increased to 111.6 ± 21.4 L min(-1). The EBC collection time decreased to 3.9 ± 1.9 min, and 1.20 ± 0.44 mL EBC were obtained in the recovery period after termination of exercise. The lactate concentration in EBC increased to 40.3 ± 23.0 µmol L(-1), and the lactate release in EBC increased to 13.6 ± 8.6 nmol min(-1) (p < 0.01). Assuming a volume of 4.3 mL water in 100 L of exhaled air (saturated with water at 37 °C), we calculated a lactate release at rest of 11.5 ± 4.3 nmol min(-1) and 48.6 ± 30.7 nmol min(-1) (p < 0.01) after exhausting exercise. Detectable releases of lactate in exhaled breath condensate were found already under resting conditions. During exhausting external load on a bicycle spiroergometer, an increase in the lactate concentration was found in arterialized blood along with an increased lactate release in EBC. The correlation between expiratory lactate release via EBC and lactate concentration in arterialized blood is studied in pursuing investigations.

Acute effects of smoking and food consumption on breath condensate pH in healthy adults

“…Number of volatile and nonvolatile metabolic products, such as ammonia, ethanol, glucose, acetaldehyde, and lactic acid, could be trapped in EBC [47][48][49][50], and some of them could, hypothetically, influence EBC pH. It should be stressed, however, that EBC represents extremely diluted respiratory droplets (on average 20,000-fold), as already mentioned [36], and it is questionable whether metabolic products of digestion are present in quantities large enough to influence EBC acidity.…”

Probing Cancer Cell Metabolism Using NMR Spectroscopy

“…One of the most widely used nuclei for NMR is the hydrogen nucleus (i.e. 1 H or proton), although other non-zero spin nuclei used include 13 C, 15 N and 31 P. It becomes apparent that this variety of NMR-visible nuclei could provide the opportunity to study almost any molecule in a biological system using single or multinuclear approaches. However, there are two reasons why this is frequently not possible: (1) the relative abundance of isotopes and (2) the sensitivity of the approach.…”

“…Liquid-state NMR spectroscopy has been used in a diverse number of bodily fl uids such as urine [ 14 ], breath condensates [ 15 ], blood plasma or serum [ 16 ], liver extracts [ 17 , 18 ], bile acid from human intestinal biopsy samples [ 19 ], and kidney perfusates [ 20 ]. A particularly attractive feature of liquid-state or high-resolution magic angle spinning NMR spectroscopy is the ability to reuse tissue or cell extracts [ 21 , 22 ].…”

Blood lactate and the lungs: from theory to practice

“…Показано, что концентрация лактата в крови коррелирует с концентрацией лактата в КВВ (r = 0,71) [28]. Таким образом, наметилась тенден ция перехода от анализа крови (инвазивного и трав матичного метода) к анализу КВВ, собираемому не инвазивно.…”

“…По данным разных исследователей, концентра ция лактата в КВВ у здоровых людей в покое колеб лется от 21,4 ± 7,7 до 31,7 ± 21,7 мкмоль / л. После ФН содержание лактата в КВВ значимо повышает ся [28][29][30].…”