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Mechanics, energetics, and crossbridge kinetics of rabbit diaphragm during congestive heart failure
Author(s) -
Lecarpentier Y.,
Chemla D.,
Blanc F. X.,
Pourny J. C.,
Joseph T.,
Riou. B.,
Coirault C.
Publication year - 1998
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.12.11.981
Subject(s) - crossbridge , heart failure , chemistry , kinetics , enzyme kinetics , medicine , myosin , biochemistry , enzyme , physics , quantum mechanics , active site
Crossbridge (CB) properties were investigated in isolated diaphragm of rabbits during congestive heart failure (CHF, n = 9) induced by chronic volume and pressure overload. This model induced cardiac hypertrophy and heart failure. Controls (C) were prepared ( n = 14). Compared to C, peak tension in CHF fell by 57% in twitch and by 40% in tetanus; V max declined by 47% in twitch and by 48% in tetanus. Our study provided an analytical means of calculating from A. F. Huxley's equations the rate constants for CB attachment and detachment, CB single force (Π), CB number per mm 3 (m′), peak mechanical efficiency (Eff max ), and turnover rate of myosin ATPase (k cat ); m′, Π, and Eff max were lower in CHF than in C in both twitch and tetanus. The marked decline in m′ and Π accounted for the fall in diaphragm strength. In the overall population of C and CHF, Eff max was linearly related to Π. Conversely, there was no relationship between V max and k cat . Dissociation between V max and k cat might be explained by the crucial role attributed to two apparently nonconserved surface ‘loops’ on the motor domain of myosin head.—Lecarpentier, Y., Chemla, D., Blanc, F. X., Pourny, J. C., Joseph, T., Riou, B., Coirault, C. Mechanics, energetics, and crossbridge kinetics of rabbit diaphragm during congestive heart failure. FASEB J. 12, 981–989 (1998)