Cardiac adaptation to endurance exercise in rats.
Endurance exercise is widely assumed to improve cardiac function in humans. This project has determined cardiac function following endurance exercise for 6 (n = 30) or 12 (n = 25) weeks in male Wistar rats (8 weeks old). The exercise protocol was 30 min/day at 0.8 km/h for 5 days/week with an endurance test on the 6th day by running at 1.2 km/h until exhaustion. Exercise endurance increased by 318% after 6 weeks and 609% after 12 weeks. Heart weight/kg body weight increased by 10.2% after 6 weeks and 24.1% after 12 weeks. Echocardiography after 12 weeks showed increases in left ventricular internal diameter in diastole (6.39 +/- 0.32 to 7.90 +/- 0.17 mm), systolic volume (49 +/- 7 to 83 +/- 11 miccrol) and cardiac output (75 +/- 3 to 107 +/- 8 ml/min) but not left wall thickness in diastole (1.74 +/- 0.07 to 1.80 +/- 0.06 mm). Isolated Langendorff hearts from trained rats displayed decreased left ventricular myocardial stiffness (22 +/- 1.1 to 19.1 +/- 0.3) and reduced purine efflux during pacing-induced workload increases. 31P-NMR spectroscopy in isolated hearts from trained rats showed decreased PCr and PCr/ATP ratios with increased creatine, AMP and ADP concentrations. Thus, this endurance exercise protocol resulted in physiological hypertrophy while maintaining or improving cardiac function.
Fenning
Andrew
A
Department of Physiology and Pharmacology, School of Biomedical Sciences, The University of Queensland, Australia.
Harrison
Glenn
G
Dwyer
Dan
D
Rose'Meyer
Roselyn
R
Brown
Lindsay
L
D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D003094:Collagen / Q000378:metabolism; D015150:Echocardiography, Doppler; D004734:Energy Metabolism; D006321:Heart / Q000502:physiology; D006651:Histocytochemistry; D008297:Male; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D011687:Purines / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014018:Tissue Distribution
D011687:Purines; D003094:Collagen