Cardiac adaptation to endurance exercise in rats

• DOI: 10.1007/978-1-4419-9238-3_8
• Publication Date: 2011-08-05T00:23:44Z
• Authors: Andrew Fenning; Glenn Harrison; Dan Dwyer; Roselyn Rose’Meyer; Lindsay Brown
• Keywords: Male; 730106 Cardiovascular system and diseases; Time Factors; Physiological hypertrophy -- Rat -- Endurance exercise -- Myocardial energy metabolism; Blood Pressure; 111501 Basic Pharmacology; Resonance Spectroscopy; Sensitivity; C1; Nitric-oxide; Physical Conditioning, Animal; Animals; Disease; Tissue Distribution; 110201 Cardiology (incl. Cardiovascular Diseases); Gene-expression; 320502 Basic Pharmacology; Cardiac Output; Rats, Wistar; Applied research; Left-ventricular Hypertrophy; Heart-failure; Histocytochemistry; Heart; Cell Biology; 920103 Cardiovascular System and Diseases; Physical fitness; Adaptation, Physiological; Echocardiography, Doppler; Rats; Cardiovascular system; Metabolism; Endurance Exercise; Purines; Biochemistry and cell biology; Hypertension; Physical Endurance; Rat; Myocardial Energy Metabolism; Quality-of-life; Collagen; Energy Metabolism; Physiological Hypertrophy; 111599 Pharmacology and Pharmaceutical Sciences not elsewhere classified

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.