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Exercise training restores contractility in collateral‐dependent myocardium independent of calcium sensitization of myofilament proteins
Author(s) -
Sarin Vandana,
Wu Xin,
Muthuchamy Mariappan,
Heaps Cristine L.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.619.21
Subject(s) - myofilament , cardiology , medicine , isometric exercise , contractility , sensitization , myocyte , immunology
Cardiac dysfunction is frequently observed in patients and animal models of coronary artery disease. For this study, we hypothesized that exercise training would improve force generation in myocardium distal to chronic coronary artery occlusion via calcium sensitization of myofilament proteins. Ameriod constrictors were surgically placed around the proximal left circumflex coronary (LCX) artery of adult female Yucatan pigs. Twenty‐two weeks post‐surgery myocardium was isolated from control (left anterior descending artery‐dependent) and collateral‐dependent (LCX‐dependent) regions of sedentary (Sed; pen‐confined) and exercise‐trained (Ex; treadmill; 5 days/wk for 14 wks) pigs. Force measurements in myocardial strips showed that percent change in force generated at stimulation frequency of 4 Hz vs. 1 Hz was higher in the collateral‐dependent region of Ex vs. Sed. Time to half peak tension and time to half relaxation in a muscle twitch at 1 Hz was similar in control and collateral‐dependent regions of the Sed and Ex pigs. Calcium sensitivity of cardiac myofilaments was unchanged in control and collateral‐dependent regions of the Sed and Ex pigs as determined by isometric tension‐pCa relationships. Thus, exercise training accentuates force generation in collateral‐dependent myocardium of Ex pigs independently of calcium sensitization of myofilament proteins. Supported by NIH HL064931.