Document Detail

Exercise training improves lusitropy by isoproterenol in papillary muscles from aged rats.
MedLine Citation:
PMID:  8904558     Owner:  NLM     Status:  MEDLINE    
Aging is associated with a decreased cardiac responsiveness to beta-adrenergic stimulation. We examined the effect of endurance exercise training of old Fischer 344 male rates on beta-adrenergic stimulation of the function of isolated left ventricular papillary muscle. Three groups were examined: sedentary mature (SM; 12-mo old), sedentary old (SO; 23-24 mo old), and exercised old (EO; 23-24 mo old) that were treadmill trained for 4-8 wk. The isometric contractile properties were studied at 0.2 Hz and 0.75 mM calcium. Without beta-adrenergic stimulation, there were no group differences for peak tension, maximum rate of tension development (+dP/dt), or maximum rate of tension dissipation (-dP/dt). The time to peak tension was longer (P < 0.05) for both EO and SO than for SM rats. Half relaxation time (RT1/2) was prolonged (P < 0.05) for SO compared with SM and EO (which did not differ). The three groups did not differ in the beta-adrenergic stimulation by isoproterenol of peak tension, -dP/dt, time to peak tension, or contraction duration. The inotropic response (+dP/dt) of SM was greater (P < 0.05) than that in SO or EO rats (which did not differ); however, the lusitropic response (RT1/2) was lesser (P < 0.05) in SO than in SM or EO rats (which did not differ). Thus exercise training of old rats improved the lusitropic response to isoproterenol without altering the age-associated impairment in inotropic response.
G E Taffet; L A Michael; C A Tate
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  81     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 Oct 
Date Detail:
Created Date:  1997-02-19     Completed Date:  1997-02-19     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1488-94     Citation Subset:  IM    
Section of Cardiovascular Sciences, Baylor College of Medicine, Houston, Texas 77030, USA.
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MeSH Terms
Adrenergic beta-Agonists / pharmacology*
Aging / physiology*
Calcium / physiology
Heart / drug effects,  physiology*
Isometric Contraction / drug effects
Isoproterenol / pharmacology*
Myocardial Contraction / drug effects,  physiology
Papillary Muscles / drug effects,  physiology
Physical Conditioning, Animal*
Rats, Inbred F344
Grant Support
Reg. No./Substance:
0/Adrenergic beta-Agonists; 7440-70-2/Calcium; 7683-59-2/Isoproterenol

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

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