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Acute and specific collagen type I degradation increases diastolic and developed tension in perfused rat papillary muscle.
- Source :
-
American journal of physiology. Heart and circulatory physiology [Am J Physiol Heart Circ Physiol] 2004 Mar; Vol. 286 (3), pp. H889-94. Date of Electronic Publication: 2003 Oct 23. - Publication Year :
- 2004
-
Abstract
- Collagen degradation is suggested to be responsible for long-term contractile dysfunction in different cardiomyopathies, but the effects of acute and specific collagen type I removal (main type in the heart muscle) on tension have not been studied. We determined the diastolic and developed tension length relations in isometric contracting perfused rat papillary muscles (perfusion pressure 60 cmH(2)O) before and after acute and specific removal of small collagen struts with the use of purified collagenase type I. At 95% of the maximal length (95%L(max)), diastolic tension increased 20.4 +/- 8.1% (P < 0.05, n = 6) and developed tension increased 15.0 +/- 6.7% after collagenase treatment compared with time controls. Treatment increased the diastolic muscle diameter by 7.1 +/- 3.4% at 95%L(max), whereas the change in diameter due to contraction was not changed. Diastolic coronary flow and normalized coronary arterial flow impediment did not change after collagenase treatment. Electron microscopy revealed that the number of small collagen struts, interconnecting myocytes, and capillaries was reduced to approximately 32% after treatment. We conclude that removal of the small collagen struts by acute and specific collagen type I degradation increases diastolic and developed tension in perfused papillary muscle. We suggest that diastolic tension is increased due to edema, whereas developed tension is increased because the removal of the struts poses a lower lateral load on the cardiac myocytes, allowing more myocyte thickening.
- Subjects :
- Animals
Collagenases pharmacology
Coronary Circulation physiology
Edema metabolism
In Vitro Techniques
Male
Microscopy, Electron, Scanning
Papillary Muscles metabolism
Papillary Muscles ultrastructure
Perfusion
Rats
Rats, Wistar
Collagen Type I metabolism
Diastole physiology
Edema physiopathology
Papillary Muscles physiopathology
Subjects
Details
- Language :
- English
- ISSN :
- 0363-6135
- Volume :
- 286
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Heart and circulatory physiology
- Publication Type :
- Academic Journal
- Accession number :
- 14576082
- Full Text :
- https://doi.org/10.1152/ajpheart.00967.2001