title: Effect of hypertonicity on contractility of isolated working rat left ventricle.
abstract: OBJECTIVE
  The aim was to evaluate the effect of hypertonic perfusate on isolated left ventricular mechanical and energetic characteristics.
  
  
  METHODS
  An isolated working rat heart model was perfused with a hyponatraemic Krebs-Heinseleit bicarbonate buffer (240 mOsmol.litre-1). To this buffer was added increasing amounts of mannitol to achieve 280, 320, and 360 mOsmol.litre-1 perfusates.
  
  
  RESULTS
  Left ventricular peak pressure, maximum time derivative of left ventricular pressure (dP/dtmax), and end systolic pressure were all increased to a maximum value at 280 or 320 mOsmol.litre-1 perfusate tonicity. A similar response was evident with cardiac output, which changed from 33.7(SEM 0.6) to 43.5(0.8) ml.min-1 following changing the perfusate tonicity from 240 to 280 mOsmol.litre-1 (p less than or equal to 0.003). However, increasing perfusate tonicity further decreased cardiac output to 36.5(1.3) ml.min-1 at 360 mOsmol.litre-1. Maximal left ventricular elastance remained unchanged during perfusion with increasing perfusate tonicities.
  
  
  CONCLUSIONS
  Changing perfusate osmolality using mannitol has a positive inotropic effect at low osmolalities and a negative inotropic effect at perfusate osmolality greater than 320 mOsm.litre-1.
authors.affiliation: Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Haifa.
authors.forename: S A
authors.initials: SA
authors.lastname: Ben-Haim
authors.forename: G
authors.initials: G
authors.lastname: Hayam
authors.forename: Y
authors.initials: Y
authors.lastname: Edoute
authors.forename: O S
authors.initials: OS
authors.lastname: Better
mesh_terms: D000818:Animals; D006982:Hypertonic Solutions / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D009924:Organ Culture Techniques; D009994:Osmolar Concentration; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D006982:Hypertonic Solutions; D008353:Mannitol