Exercise training improves lusitropy by isoproterenol in papillary muscles from aged rats

George E. Taffet, Lloyd A. Michael, and Charlotte A. Tate Sections of Cardiovascular Sciences and Geriatrics, Baylor College of Medicine, Houston 77030; and Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204 Received 15 February 1995; accepted in f...

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Published in:Journal of applied physiology (1985) 1996-10, Vol.81 (4), p.1488-1494
Main Authors: Taffet, George E, Michael, Lloyd A, Tate, Charlotte A
Format: Article
Language:English
Subjects:
Adrenergic beta-Agonists - pharmacology
Aging - physiology
Animals
Biological and medical sciences
Calcium - physiology
Fundamental and applied biological sciences. Psychology
Heart
Heart - drug effects
Heart - physiology
In Vitro Techniques
Isometric Contraction - drug effects
Isoproterenol - pharmacology
Male
Myocardial Contraction - drug effects
Myocardial Contraction - physiology
Papillary Muscles - drug effects
Papillary Muscles - physiology
Physical Conditioning, Animal
Rats
Rats, Inbred F344
Vertebrates: cardiovascular system
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Summary:George E. Taffet, Lloyd A. Michael, and Charlotte A. Tate Sections of Cardiovascular Sciences and Geriatrics, Baylor College of Medicine, Houston 77030; and Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas 77204 Received 15 February 1995; accepted in final form 17 April 1996. Taffet, George E., Lloyd A. Michael, and Charlotte A. Tate. Exercise training improves lusitropy by isoproterenol in papillary muscles from aged rats. J. Appl. Physiol. 81(4): 1488-1494, 1996. Aging is associated with a decreased cardiac responsiveness to -adrenergic stimulation. We examined the effect of endurance exercise training of old Fischer 344 male rats on -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 -adrenergic stimulation, there were no group differences for peak tension, maximum rate of tension development (+dP/d t ), or maximum rate of tension dissipation ( dP/d t ). The time to peak tension was longer ( P  
ISSN:8750-7587
1522-1601
DOI:10.1152/jappl.1996.81.4.1488