Document Detail

The effect of chronic bradycardial pacing on the oxidative capacity in rabbit hearts.
MedLine Citation:
PMID:  3363229     Owner:  NLM     Status:  MEDLINE    
Blood flow and oxygen consumption were estimated in isolated hearts from control rabbits or animals with chronic bradycardia achieved by transvenous atrial pacing for 4 weeks; these parameters were related to ultrastructural changes. Chronic reduction of heart frequency to about 50% of control values resulted in an increased capillary/fibre ratio (1.43 +/- 0.07 in paced, 1.26 +/- 0.07 in control hearts), increased capillary density (2339 +/- 148 vs 1897 +/- 95) and increased volume density of mitochondria (36.36 +/- 1.28% vs 31.38 +/- 1.7%), in paced and control hearts, respectively, with no signs of heart hypertrophy (fibre diameters 28.5 micron in both groups). Maximal blood flow (3 ml.g-1.min-1) was similar in paced and control hearts. Maximal oxygen consumption (achieved by a gradual increase in preload and increase in force of contraction by noradrenalin infusion) in paced hearts was significantly higher than in control hearts and was achieved by a higher oxygen extraction. This could be due both to the increased volume density of mitochondria and to a more homogeneous distribution of flow through an enlarged capillary bed. The increased oxidative capacity induced by chronic bradycardial pacing can explain improved maximal cardiac work found under these conditions previously in vivo.
O Hudlicka; A J Wright; H Hoppeler; E Uhlmann
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiration physiology     Volume:  72     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1988 Apr 
Date Detail:
Created Date:  1988-06-02     Completed Date:  1988-06-02     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  1-12     Citation Subset:  IM    
Department of Physiology, University of Birmingham Medical School, U.K.
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MeSH Terms
Bradycardia / physiopathology*
Cardiac Pacing, Artificial
Coronary Circulation
Mitochondria, Heart / ultrastructure
Myocardium / metabolism*,  ultrastructure
Oxygen Consumption*
Time Factors

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