title: Neonatal murine heart slices. A robust model to study ventricular isometric contractions.
abstract: OBJECTIVE
  Cardiac function is increasingly studied using murine models. However, current multicellular preparations to investigate contractile properties have substantial technical and biological limitations and are especially difficult to apply to the developing murine heart.
  
  
  METHODS
  Newborn murine hearts were cut with a vibratome into viable tissue slices. The structural and functional integrity of the tissue was shown by histology, ATP content and sharp electrode recordings.
  
  
  RESULTS
  Within the first 48 hours after slicing structure remained intact without induction of apoptosis. ATP concentrations and action potential parameters were comparable to those of physiological tissue. Isometric force measurements demonstrated a physiological force-frequency relationship with a ;primary-phase' negative force-frequency relationship up to 1-2 Hz and a ;secondary-phase' positive force-frequency relationship up to 8 Hz. (-)-Isoproterenol (10(-6) mol/l) increased active force to 251 +/- 35% (n=15) of baseline values and shortened relaxation times indicating a preserved beta-adrenergic regulation of contraction. Changes of the force-frequency relationship after application of ryanodine and nifedipine indicated functionality of calcium release from the sarcoplasmic reticulum and of L-type calcium channels.
  
  
  CONCLUSIONS
  Generation of viable, physiological intact ventricular slices from neonatal hearts is feasible and provides a robust model to study loaded contractions.
authors.affiliation: Pediatric Cardiology, University of Cologne, Cologne, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Pillekamp
authors.forename: Marcel
authors.initials: M
authors.lastname: Halbach
authors.forename: Michael
authors.initials: M
authors.lastname: Reppel
authors.forename: Olga
authors.initials: O
authors.lastname: Rubenchyk
authors.forename: Kurt
authors.initials: K
authors.lastname: Pfannkuche
authors.forename: Jiao-Ya
authors.initials: JY
authors.lastname: Xi
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.forename: Narayanswami
authors.initials: N
authors.lastname: Sreeram
authors.forename: Konrad
authors.initials: K
authors.lastname: Brockmeier
authors.forename: Juergen
authors.initials: J
authors.lastname: Hescheler
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D009543:Nifedipine / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012433:Ryanodine / Q000494:pharmacology; D016276:Ventricular Function
chemical_list: D011943:Receptors, Adrenergic, beta; D012433:Ryanodine; D009543:Nifedipine