Beschreibung:
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<jats:list-item><jats:p>The aim of this study was to investigate the effect of nicotinamide‐adenine dinucleotide (NADH) supplementation on the metabolic condition of isolated guinea‐pig ventricular cardiomyocytes. The pinacidil‐primed ATP‐dependent potassium current <jats:italic>I</jats:italic><jats:sub>K(ATP)</jats:sub> was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured.</jats:p></jats:list-item>
<jats:list-item><jats:p>Membrane currents were studied using the patch‐clamp technique in the whole‐cell recording mode at 36–37°C. Adenine nucleotides were determined by HPLC.</jats:p></jats:list-item>
<jats:list-item><jats:p>Under physiological conditions (4.3 m<jats:sc>M</jats:sc> ATP in the pipette solution, ATP<jats:sub>i</jats:sub>) <jats:italic>I</jats:italic><jats:sub>K(ATP)</jats:sub> did not contribute to basal electrical activity.</jats:p></jats:list-item>
<jats:list-item><jats:p>The ATP‐dependent potassium (K<jats:sub>(ATP)</jats:sub>) channel opener pinacidil activated <jats:italic>I</jats:italic><jats:sub>K(ATP)</jats:sub> dependent on [ATP]<jats:sub>i</jats:sub> showing a significantly more pronounced activation at lower (1 m<jats:sc>M</jats:sc>) [ATP]<jats:sub>i</jats:sub>.</jats:p></jats:list-item>
<jats:list-item><jats:p>Supplementation of cardiomyocytes with 300 <jats:italic>μ</jats:italic>g ml<jats:sup>−1</jats:sup> NADH (4–6 h) resulted in a significantly reduced <jats:italic>I</jats:italic><jats:sub>K(ATP)</jats:sub> activation by pinacidil compared to control cells. The current density was 13.8±3.78 (<jats:italic>n</jats:italic>=6) <jats:italic>versus</jats:italic> 28.9±3.38 pA pF<jats:sup>−1</jats:sup> (<jats:italic>n</jats:italic>=19; <jats:italic>P</jats:italic><0.05).</jats:p></jats:list-item>
<jats:list-item><jats:p>Equimolar amounts of the related compounds nicotinamide and NAD<jats:sup>+</jats:sup> did not achieve a similar effect like NADH.</jats:p></jats:list-item>
<jats:list-item><jats:p>Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6±1.88 nmol mg<jats:sup>−1</jats:sup> protein <jats:italic>versus</jats:italic> control: 35.4±2.57 nmol mg<jats:sup>−1</jats:sup> protein, <jats:italic>P</jats:italic><0.000005).</jats:p></jats:list-item>
<jats:list-item><jats:p>These data show that supplementation of guinea‐pig ventricular cardiomyocytes with NADH results in a decreased activation of <jats:italic>I</jats:italic><jats:sub>K(ATP)</jats:sub> by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration.</jats:p></jats:list-item>
<jats:list-item><jats:p>Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP.</jats:p></jats:list-item>
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</jats:p><jats:p><jats:italic>British Journal of Pharmacology</jats:italic> (2003) <jats:bold>139</jats:bold>, 749–754. doi:<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" xlink:href="10.1038/sj.bjp.0705300">10.1038/sj.bjp.0705300</jats:ext-link></jats:p>