Journal
JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY
Volume 34, Issue 1, Pages 63-73Publisher
ELSEVIER SCI LTD
DOI: 10.1006/jmcc.2001.1490
Keywords
remodeled myocardium; excitation-contraction coupling; hibernating myocardium; myocardial hypertrophy; Ca2+ handling
Categories
Funding
- NCRR NIH HHS [RR00151] Funding Source: Medline
- NHLBI NIH HHS [HL62442, HL59526, HL61476, HL33107, HL33065, HL57980, HL69020, HL59139, HL65182, HL65183] Funding Source: Medline
- NIGMS NIH HHS [GM54169] Funding Source: Medline
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [P01HL069020, R37HL033107, R01HL061476, R01HL057980, R01HL065183, P01HL059139, R01HL062442, R01HL033107, R01HL033065, R29HL057980, R01HL065182] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM054169] Funding Source: NIH RePORTER
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Following myocardial infarction (MI), the left ventricle undergoes progressive dilatation and eccentric hypertrophy. i.e., remodeling, which is greater in the adjacent than the remote region, The cellular mechanisms underlying these regional differences were studied. One (n=5) and 8 weeks (n=8) after anteroapical MI in sheep, cardiac myocytes were isolated from the adjacent and remote regions. At 8 weeks after MI, myocyte function in the remote region was not different from values either in sham controls (n=3) or animals 1 week after MI. At 8 weeks after MI myocyte contractile function (% contraction) was decreased, P<0.01, in the adjacent region (6.4 +/- 0.4%). as compared with the remote region (8.8 +/- 0.5%) and was associated with decreased amplitude of Ca2+ transients (adjacent, 0.69 +/- 0.09 v remote, 1.08 +/- 0.20, P<0.05) and L-type Ca2+ current density (adjacent. 3.6 +/- 0.2 v remote, 4.8 +/- 0.2 pA/pF, P<0.05). Relaxation was also impaired significantly in myocytes from the adjacent region, associated with decreased protein levels of SERCA2a. The myocytes were hypertrophied more in the adjacent region than the remote region. Furthermore, focal areas of central myofibrillar lysis and increased glycogen deposition were observed in the adjacent region. These results indicate that impaired excitation-contraction coupling underlies dysfunction of myocytes from the adjacent non-infarcted myocardium after chronic MI, even in the absence of heart failure. Hypertrophy is implicated as the mechanism, since these changes were noted at 8 weeks, but not at 1 week after MI. (C) 2002 Elsevier Science Ltd.
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