Document Detail

The rate of force generation by the myocardium is not influenced by afterload.
MedLine Citation:
PMID:  9686169     Owner:  NLM     Status:  MEDLINE    
The influence of afterload on the rate of force generation by the myocardium was investigated using two types of preparations: the in situ dog heart (dP/dt) and isolated papillary muscle of rats (dT/dt). Thirteen anesthetized, mechanically ventilated and thoracotomized dogs were submitted to pharmacological autonomic blockade (3.0 mg/kg oxprenolol plus 0.5 mg/kg atropine). A reservoir connected to the left atrium permitted the control of left ventricular end-diastolic pressure (LVEDP). A mechanical constriction of the descending thoracic aorta allowed to increase the systolic pressure in two steps of 20 mmHg (conditions H1 and H2) above control values (condition C). After arterial pressure elevations (systolic pressure C: 119 +/- 8.1; H1: 142 +/- 7.9; H2: 166 +/- 7.7 mmHg; P < 0.01), there were no significant differences in heart rate (C: 125 +/- 13.9; H1: 125 +/- 13.5; H2: 123 +/- 14.1 bpm; P > 0.05) or LVEDP (C: 6.2 +/- 2.48; H1: 6.3 +/- 2.43; H2: 6.1 +/- 2.51 mmHg; P > 0.05). The values of dP/dt did not change after each elevation of arterial pressure (C: 3,068 +/- 1,057; H1: 3,112 +/- 996; H2: 3,086 +/- 980 mmHg/s; P > 0.05). In isolated rat papillary muscle, an afterload corresponding to 50% and 75% of the maximal developed tension did not alter the values of the maximum rate of tension development (100%: 78 +/- 13; 75%: 80 +/- 13; 50%: 79 +/- 11 g mm-2 s-1, P > 0.05). The results show that the rise in afterload per se does not cause changes in dP/dt or dT/dt.
J R Fioretto; M P Okoshi; K Okoshi; A C Cicogna; R C Bonatto; C R Padovani; P J Tucci
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brazilian journal of medical and biological research = Revista brasileira de pesquisas médicas e biológicas / Sociedade Brasileira de Biofísica ... [et al.]     Volume:  30     ISSN:  0100-879X     ISO Abbreviation:  Braz. J. Med. Biol. Res.     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1998-10-05     Completed Date:  1998-10-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8112917     Medline TA:  Braz J Med Biol Res     Country:  BRAZIL    
Other Details:
Languages:  eng     Pagination:  1471-7     Citation Subset:  IM    
Departamento de Pediatria, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, SP, Brasil.
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MeSH Terms
Heart / physiology*
Isometric Contraction / physiology
Multivariate Analysis
Myocardial Contraction / physiology*
Papillary Muscles / physiology*
Rats, Wistar
Ventricular Function, Left / physiology*

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