Capillary electrophoresis (CE) with contactless conductivity detection (C4D) represents a strong tool for determining amino acids in clinical samples. This chapter provides detailed instructions for CE/C4D determination of the branched-chain amino acids (BCAAs) valine, isoleucine, and leucine in human plasma, which can be readily employed in physiological studies. Baseline separation of all the BCAAs is achieved on a short separation length equal to 18 cm in optimized background electrolyte consisting of 3.2 M acetic acid dissolved in 20% v/v methanol with addition of 1.0% v/v INST-coating solution. The analysis time does not exceed 3 min and the limit of detection is 0.4 μM for all BCAAs. The pretreatment of human plasma is very simple and is based on fourfold plasma dilution by acetonitrile and subsequent filtration. Only 50 μL of plasma is used for the analysis. The high sensitivity of the CE/C4D method is achieved by injecting a large volume of sample, combined with application of negative pressure to flush the acetonitrile zone out of the capillary.

• Klíčová slova
• Branched-chain amino acids, Capillary electrophoresis, Contactless conductivity detection, Human plasma, Large-volume sample stacking, Pressure-assisted analysis, Rapid determination,
• MeSH
• elektrická vodivost * MeSH
• elektroforéza kapilární metody   MeSH
• fyziologie * MeSH
• kalibrace MeSH
• lidé MeSH
• referenční standardy MeSH
• větvené aminokyseliny krev   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• větvené aminokyseliny MeSH

BACKGROUND: Aim of the study was to compare metabolic response of leg skeletal muscle during functional electrical stimulation-driven unloaded cycling (FES) to that seen during volitional supine cycling. METHODS: Fourteen healthy volunteers were exposed in random order to supine cycling, either volitional (10-25-50 W, 10 min) or FES assisted (unloaded, 10 min) in a crossover design. Whole body and leg muscle metabolism were assessed by indirect calorimetry with concomitant repeated measurements of femoral venous-arterial differences of blood gases, glucose, lactate and amino acids. RESULTS: Unloaded FES cycling, but not volitional exercise, led to a significant increase in across-leg lactate production (from -1.1±2.1 to 5.5±7.4 mmol/min, p<0.001) and mild elevation of arterial lactate (from 1.8±0.7 to 2.5±0.8 mM). This occurred without widening of across-leg veno-arterial (VA) O2 and CO2 gaps. Femoral SvO2 difference was directly proportional to VA difference of lactate (R2 = 0.60, p = 0.002). Across-leg glucose uptake did not change with either type of exercise. Systemic oxygen consumption increased with FES cycling to similarly to 25W volitional exercise (138±29% resp. 124±23% of baseline). There was a net uptake of branched-chain amino acids and net release of Alanine from skeletal muscle, which were unaltered by either type of exercise. CONCLUSIONS: Unloaded FES cycling, but not volitional exercise causes significant lactate production without hypoxia in skeletal muscle. This phenomenon can be significant in vulnerable patients' groups.

• MeSH
• aminokyseliny metabolismus   MeSH
• arteria femoralis metabolismus   MeSH
• bérec MeSH
• cyklistika fyziologie   MeSH
• dospělí MeSH
• elektrická stimulace MeSH
• klinické křížové studie MeSH
• kosterní svaly metabolismus   MeSH
• kyselina mléčná biosyntéza   krev   MeSH
• kyslík krev   MeSH
• lidé MeSH
• mladý dospělý MeSH
• nepřímá kalorimetrie MeSH
• oxid uhličitý krev   MeSH
• spotřeba kyslíku MeSH
• supinační poloha fyziologie   MeSH
• terapie cvičením metody   MeSH
• vena femoralis metabolismus   MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny MeSH
• kyselina mléčná MeSH
• kyslík MeSH
• oxid uhličitý MeSH