Document Detail

Beneficial effects of myocyte preconditioning on contractile processes after cardioplegic arrest.
MedLine Citation:
PMID:  8572767     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Myocardial precondition, which can be achieved through short intervals of ischemia or hypoxia followed by reperfusion, protects the myocardium with subsequent prolonged periods of ischemia. Accordingly, the present study tested the hypothesis that hypoxic preconditioning before cardioplegic arrest would have direct and beneficial effects on myocyte contractile processes with reperfusion. METHODS: Left ventricular porcine myocytes (n = 335) were randomly assigned to one of three treatments: normothermia, maintained in cell media (37 degrees C, 2 hours); cardioplegia, hyperkalemic arrest (24 mEq K+, 4 degrees C, 2 hours) followed by normothermic reperfusion; preconditioning, hypoxia (20 minutes) and reperfusion (20 minutes), and then followed by cardioplegic arrest and rewarming. Myocyte velocity of shortening was measured using computer-assisted videomicroscopy at baseline and with beta-adrenergic receptor stimulation with isoproterenol (25 nmol/L). RESULTS: In the cardioplegia group, myocyte function was reduced at baseline (22 +/- 1 versus 57 +/- 2 microns/s) and with beta-adrenergic receptor stimulation (81 +/- 5 versus 156 +/- 7 microns/s) compared to normothermic controls (p < 0.05). Preconditioning improved myocyte function at baseline (38 +/- 2 microns/s) and with beta-adrenergic receptor stimulation (130 +/- 6 microns/s) compared to the cardioplegic alone group (p < 0.05). CONCLUSIONS: The important findings from this study are twofold. First, preconditioning can be induced directly at the level of the myocyte, independent of nonmyocyte populations and extracellular influences. Second, myocyte preconditioning provides protective effects on myocyte function and beta-adrenergic responsiveness after cardioplegic arrest and rewarming. These findings suggest that preconditioning may provide a novel approach in protecting myocyte contractile processes during cardioplegic arrest.
J L Zellner; L Hebbar; F A Crawford; R Mukherjee; F G Spinale
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Annals of thoracic surgery     Volume:  61     ISSN:  0003-4975     ISO Abbreviation:  Ann. Thorac. Surg.     Publication Date:  1996 Feb 
Date Detail:
Created Date:  1996-03-06     Completed Date:  1996-03-06     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  15030100R     Medline TA:  Ann Thorac Surg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  558-64     Citation Subset:  AIM; IM; S    
Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston 29425, USA.
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MeSH Terms
Adaptation, Physiological
Heart Arrest, Induced / methods*
Hypothermia, Induced
Myocardial Contraction / physiology*
Myocardial Ischemia / physiopathology
Myocardial Reperfusion
Myocardium / cytology
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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