Publication
Title
Mechanics and energetics of myosin molecular motors from nonpregnant human myometrium
Author
Abstract
Mechanical properties of spontaneously contracting isolated nonpregnant human myometrium (NPHM) were investigated throughout the whole continuum of load from zero load up to isometry. This made it possible to assess the three-dimensional tension-velocity-length (T-V-L) relationship characterizing the level of contractility and to determine crossbridge (CB) kinetics of myosin molecular motors. Seventy-seven muscle strips were obtained from hysterectomy in 42 nonpregnant patients. Contraction and relaxation parameters were measured during spontaneous mechanical activity. The isotonic tension-peak velocity (T-V) relationship was hyperbolic in 30 cases and nonhyperbolic in 47 cases. When the T-V relationship was hyperbolic, the Huxley formalism could be used to calculate CB kinetics and CB unitary force. At the whole muscle level and for a given isotonic load level, part of the V-L phase plane showed a common pathway, so that a given instantaneous length corresponded to only one possible instantaneous velocity, independent of time and initial length. At the molecular level, rate constants for CB attachment and detachment were dramatically low, ∼100 times lower than those of striated muscles, and ∼5 to 10 times lower than those of other smooth muscles. The CB unitary force was ∼1.4 ± 0.1 pN. NPHM shared similar basic contractile properties with striated muscles, reflected in the three-dimensional T-V-L relationship characterizing the contractile level. Low CB attachment and detachment rate constants made it possible to generate normal CB unitary force and normal muscle tension in NPHM, even though it contracted extremely slowly compared with other muscles.
Language
English
Source (journal)
Journal of applied physiology / American Physiological Society. - Washington, D.C.
Publication
Washington, D.C. : 2011
ISSN
8750-7587
Volume/pages
111:4(2011), p. 1096-1105
ISI
000295972000020
Full text (Publishers DOI)
Full text (publishers version - intranet only)
UAntwerpen
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Publication type
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Affiliation
Publications with a UAntwerp address
External links
Web of Science
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Creation 17.01.2012
Last edited 09.05.2017
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