Two methods of capillary electrophoresis with contactless conductivity detection have been developed for monitoring the levels of glucose and lactate in clinical samples. The separations are performed in uncoated fused silica capillaries with inner diameter 10 or 20 μm, total length 31.5 cm, length to detector 18 cm, using an Agilent electrophoretic instrument with an integrated contactless conductivity detector. Glucose is determined in optimized background electrolyte, 50 mM NaOH with pH 12.6 and 2-deoxyglucose is used as an internal standard; the determination of lactate is performed in 40 mM CHES/NaOH with pH 9.4 and lithium cations as an internal standard. Both substances are determined in minimal volumes of (1) nutrient media after cell incubation, and (2) microdialysates of human adipose tissue; after dilution and filtration as the only treatment of the sample. The migration time of glucose is 2.5 min and that of lactate is 1.5 min with detection limits at the micromolar concentration level. The developed techniques are suitable for sequential monitoring of glucose and lactate over time during metabolic experiments.

• Klíčová slova
• Capillary electrophoresis, Cell incubation, Contactless conductivity detection, Glucose, Lactate, Microdialysis, Rapid determination,
• MeSH
• elektrická vodivost * MeSH
• elektroforéza kapilární metody   MeSH
• glukosa analýza   MeSH
• kalibrace MeSH
• kultivační média chemie   MeSH
• kultivované buňky MeSH
• kyselina mléčná analýza   MeSH
• lidé MeSH
• mikrodialýza metody   MeSH
• tuková tkáň MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glukosa MeSH
• kultivační média MeSH
• kyselina mléčná MeSH

Objective: Metformin was shown to exert an antilipolytic action in adipose tissue (AT) that might mediate beneficial effects on lipid metabolism in diabetic patients. However, during exercise, the inhibition of induced lipolysis in AT would limit the energy substrate supply for working muscle. Thus, the aim of this study was to investigate whether metformin exerts inhibitory effect on exercise-induced lipolysis in subcutaneous adipose tissue (SCAT) (Moro et al., 2007) in humans. Approach: Ten healthy lean men underwent two exercise sessions consisting of 60 min of cycling on bicycle ergometer combined with (a) orally administered metformin and (b) metformin locally administered into SCAT. Microdialysis was used to assess lipolysis in situ in SCAT. Glycerol, metformin and lactate were measured in dialysate and plasma by enzyme colorimetric kits and capillary electrophoresis. Results: Metformin levels increased continuously in plasma during 3 h after oral administration, and peaked after 3.5 h (peak concentration 4 μg/ml). Metformin was detected in dialysate outflowing from SCAT and showed a similar time-course as that in plasma with the peak concentration of 1.3 μg/ml. The lipolytic rate in SCAT (assessed as glycerol release) increased in response to exercise (4.3 ± 0.5-fold vs. basal; p = 0.002) and was not suppressed either by local or oral metformin administration. The lactate levels increased in plasma and in dialysate from SCAT after 30-60 min of exercise (3.6-fold vs. basal; p = 0.015; 2.75-fold vs. basal; p = 0.002, respectively). No effect of metformin on lactate levels in SCAT dialysate or in plasma during exercise was observed. Conclusion: Metformin did not reduce the exercise-induced lipolysis in SCAT. This suggests that metformin administration does not interfere with the lipid mobilization and energy substrate provision during physical activity.

• Klíčová slova
• exercise, human adipose tissue, lactate, lipolysis, metformin, microdialysis,
• Publikační typ
• časopisecké články MeSH