title: To establish a pharmacological experimental platform for the study of cardiac hypoxia using the microelectrode array.
abstract: BACKGROUND
  Simultaneous recording of electrical potentials from multiple cells may be useful for physiological and pharmacological research. The present study aimed to establish an in vitro cardiac hypoxia experimental platform on the microelectrode array (MEA).
  
  
  METHODS
  Embryonic rat cardiac myocytes were cultured on the MEAs. Following >or=90 min of hypoxia, changes in lactate production (mM), pH, beat frequency (beats per min, bpm), extracellular action potential (exAP) amplitude, and propagation velocity between the normoxic and hypoxic cells were compared.
  
  
  RESULTS
  Under hypoxia, the beat frequency of cells increased and peaked at around 42.5 min (08.1+/-3.2 bpm). The exAP amplitude reduced as soon as the cells were exposed to the hypoxic medium, and this reduction increased significantly after approximately 20 min of hypoxia. The propagation velocity of the hypoxic cells was significantly lower than that of the control throughout the entire 90+ min of hypoxia. The rate of depolarisation and Na(+) signal gradually reduced over time, and these changes had a direct effect on the exAP duration.
  
  
  CONCLUSIONS
  The extracellular electrophysiological measurements allow a partial reconstruction of the signal shape and time course of the underlying hypoxia-associated physiological changes. The present study showed that the cardiac myocyte-integrated MEA may be used as an experimental platform for the pharmacological studies of cardiovascular diseases in the future.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong (CUHK), Shatin, Hong Kong. chi-kong_yeung@lycos.com
authors.forename: Chi-Kong
authors.initials: CK
authors.lastname: Yeung
authors.forename: Frank
authors.initials: F
authors.lastname: Sommerhage
authors.forename: Günter
authors.initials: G
authors.lastname: Wrobel
authors.forename: Jessica Ka-Yan
authors.initials: JK
authors.lastname: Law
authors.forename: Andreas
authors.initials: A
authors.lastname: Offenhäusser
authors.forename: John Anthony
authors.initials: JA
authors.lastname: Rudd
authors.forename: Sven
authors.initials: S
authors.lastname: Ingebrandt
authors.forename: Mansun
authors.initials: M
authors.lastname: Chan
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D009994:Osmolar Concentration; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007773:Lactates