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NADH supplementation decreases pinacidil‐primed I K(ATP) in ventricular cardiomyocytes by increasing intracellular ATP
Author(s) -
Pelzmann Brigitte,
Hallström Seth,
Schaffer Peter,
Lang Petra,
Nadlinger Karl,
Birkmayer George D,
Vrecko Karoline,
Reibnegger Gilbert,
Koidl Bernd
Publication year - 2003
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705300
Subject(s) - pinacidil , intracellular , nad+ kinase , chemistry , nicotinamide adenine dinucleotide , adenine nucleotide , nucleotide , biochemistry , adenosine triphosphate , biophysics , biology , endocrinology , enzyme , glibenclamide , gene , diabetes mellitus
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 I K(ATP) was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured. 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. Under physiological conditions (4.3 m M ATP in the pipette solution, ATP i ) I K(ATP) did not contribute to basal electrical activity. The ATP‐dependent potassium (K (ATP) ) channel opener pinacidil activated I K(ATP) dependent on [ATP] i showing a significantly more pronounced activation at lower (1 m M ) [ATP] i . Supplementation of cardiomyocytes with 300 μ g ml −1 NADH (4–6 h) resulted in a significantly reduced I K(ATP) activation by pinacidil compared to control cells. The current density was 13.8±3.78 ( n =6) versus 28.9±3.38 pA pF −1 ( n =19; P <0.05). Equimolar amounts of the related compounds nicotinamide and NAD + did not achieve a similar effect like NADH. Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6±1.88 nmol mg −1 protein versus control: 35.4±2.57 nmol mg −1 protein, P <0.5). These data show that supplementation of guinea‐pig ventricular cardiomyocytes with NADH results in a decreased activation of I K(ATP) by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration. Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP.British Journal of Pharmacology (2003) 139 , 749–754. doi: 10.1038/sj.bjp.0705300