Swim training improves myocardial resistance to ischemia in rats

Vittoria Margonato, G. Milano, S. Allibardi, G. Merati, R. De Jonge, M. Samaja

Research output: Contribution to journalArticlepeer-review

Abstract

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 incresed 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 ischemia preconditioning.

Original languageEnglish
Pages (from-to)163-167
Number of pages5
JournalInternational Journal of Sports Medicine
Volume21
Issue number3
DOIs
Publication statusPublished - 2000

Keywords

  • Isolated hearts
  • Myocardial performance
  • Reperfusion injury

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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