Effect of Physical Training on the Mechanical and Metabolic Response of the Rat Heart to Hypoxia

To study the effects of physical conditioning on cardiac function and metabolism during hypoxia, rats were conditioned by swimming. Their isolated hearts and hearts of sedentary rats were studied under isovolumic conditions and also while performing external work. During isovolumic performance only...

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Bibliographic Details
Published in:Circulation research 1972-04, Vol.30 (4), p.418-429
Main Authors: SCHEUER, JAMES, STEZOSKI, S William
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Animals
Blood Pressure
Body Weight
Cardiac Output
Coronary Circulation
Glycogen - metabolism
Heart - anatomy & histology
Heart - physiopathology
Hypoxia - metabolism
Hypoxia - physiopathology
Lactates - metabolism
Male
Myocardium - metabolism
Oxygen - blood
Oxygen Consumption
Partial Pressure
Phosphocreatine - metabolism
Physical Education and Training
Pyruvates - metabolism
Rats
Rats, Inbred Strains
Space life sciences
Time Factors
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Summary:To study the effects of physical conditioning on cardiac function and metabolism during hypoxia, rats were conditioned by swimming. Their isolated hearts and hearts of sedentary rats were studied under isovolumic conditions and also while performing external work. During isovolumic performance only minimal improvement in hypoxic cardiac performance was observed because of conditioning. While performing external work during hypoxia cardiac output and cardiac work were approximately twice as great in hearts from conditioned rats as in those from sedentary rats. There were also slightly higher peak systolic pressures and mean left ventricular systolic pressures during hypoxia. Oxygen delivery and lactate production during hypoxia were the same in hearts from conditioned and sedentary rats as were myocardial NADH fluorescence, residual high-energy phosphate stores, and myocardial glycogen levels. External efficiency in experiments on working rat hearts was twice as great during hypoxia in hearts from conditioned rats as in those fromsedentary rats. The data suggest that hearts of conditioned rats have enhanced pumping capacity when subjected to hypoxia compared with hearts of sedentary rats. Oxygen delivery and energy formation during hypoxia are not improved in hearts of conditioned animals. The major reason for improved performance appears to be more efficient energy utilization for external cardiac work.
ISSN:0009-7330
1524-4571
DOI:10.1161/01.RES.30.4.418