Int J Sports Med 2000; 21(3): 163-167
DOI: 10.1055/s-2000-8876
Physiology and Biochemistry
Georg Thieme Verlag Stuttgart ·New York

Swim Training Improves Myocardial Resistance to Ischemia in Rats

V. Margonato, G. Milano, S. Allibardi, G. Merati1 , R. de Jonge2 , M. Samaja3
  • 1 Dipartimento di Scienze e Tecnologie Biomediche, Università degli Studi di Milano, Italy
  • 2 Istituto Superiore di Educazione Fisica della Lombardia, Milano, Italy
  • 3 Cardiochemical Laboratory, Thoraxcenter, Erasmus University Rotterdam, The Netherlands
  • 4 Dipartimento di Medicina, Chirurgia e Odontoiatria, Polo San Paolo, Università degli Studi di Milano, Italy
Further Information

Publication History

Publication Date:
31 December 2000 (online)

As the relationship between training and ischemic heart disease is not yet unraveled, we test the hypothesis that, in a model free from environmental, behavioural, and neuro-hormonal factors, endurance training improves myocardial resistance to ischemia. As carbohydrate metabolism is relevant for myocardial resistance to ischemia, we also test whether hyperglycemia blunts the protective effect of training. Eight-week old rats were randomly assigned to four groups (n = 6 - 8): sedentary or trained (3-week swim program, up to 2 h/day), and normal or high-carbohydrate diet (50 g/l sucrose in drinking water). Excised hearts were perfused isovolumically (flow = 15 ml/min) with Krebs-Henseleit (2 mM free Ca++, 11 mM glucose, pH 7.38 ± 0.02, PO2 = 670 ± 6 mmHg, PCO2 = 43 ± 1 mmHg, mean ± SE), exposed to 60 min low-flow (1.5 ml/min) ischemia, and then reperfused for 30 min (15 ml/min). In normally fed rats training increased the stroke volume index (97.5 ± 13.0 vs. 72.6 ± 6.2 µl, P = 0.05), depressed diastolic contracture (+2.3 ±2.0 vs. +24.2 ± 6.7 mmHg, P = 0.02), improved the recovery of developed pressure · heart rate (33.8 ± 2.3 vs. 24.1 ± 3.3 mmHg/min/1000, P = 0.05), and decreased arrhythmias (P = 0.05). In high-carbohydrate-fed rats training induced myocardial hypertrophy (1.95 ± 0.08 vs. 1.67 ± 0.03 g, P = 0.02) and decreased arrhythmias but did not affect stroke volume, developed pressure · heart rate, and diastolic contracture. Thus endurance training improves myocardial resistance to ischemia but a high-carbohydrate diet partially blunts this protection. The occurrence of an inducible alteration able to modulate myocardial tolerance to ischemia may give clues to extend our knowledge of ischemic preconditioning.

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