NDLI: Endothermic force generation, temperature-jump experiments and effects of increased [MgADP] in rabbit psoas muscle fibres

Content Provider	PubMed Central
Author	Coupland, Me Pinniger, Gj Ranatunga, Kw
Copyright Year	2005
Abstract	We studied, by experiment and by kinetic modelling, the characteristics of the force increase on heating (endothermic force) in muscle. Experiments were done on maximally Ca2+-activated, permeabilized, single fibres (length ∼2 mm; sarcomere length, 2.5 μm) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1 and ionic strength was 200 mm. A small-amplitude (∼3°C) rapid laser temperature-jump (0.2 ms T-jump) at 8–9°C induced a tension rise to a new steady state and it consisted of two (fast and slow) exponential components. The T-jump-induced tension rise became slower as [MgADP] was increased, with half-maximal effect at 0.5 mm[MgADP]; the pre- and post-T-jump tension increased ∼20% with 4 mm added [MgADP]. As determined by the tension change to small, rapid length steps (<1.4%L 0 complete in <0.5 ms), the increase of force by [MgADP] was not associated with a concomitant increase of stiffness; the quick tension recovery after length steps (Huxley–Simmons phase 2) was slower with added MgADP. In steady-state experiments, the tension was larger at higher temperatures and the plot of tension versus reciprocal absolute temperature was sigmoidal, with a half-maximal tension at 10–12°C; the relation with added 4 mm MgADP was shifted upwards on the tension axis and towards lower temperatures. The potentiation of tension with 4 mm added MgADP was 20–25% at low temperatures (∼5–10°C), but ∼10% at the physiological temperatures (∼30°C). The shortening velocity was decreased with increased [MgADP] at low and high temperatures. The sigmoidal relation between tension and reciprocal temperature, and the basic effects of increased [MgADP] on endothermic force, can be qualitatively simulated using a five-step kinetic scheme for the crossbridge/A-MATPase cycle where the force generating conformational change occurs in a reversible step before the release of inorganic phosphate (Pi), it is temperature sensitive (Q 10 of ∼4) and the release of MgADP occurs by a subsequent, slower, two-step mechanism. Modelling shows that the sigmoidal relation between force and reciprocal temperature arises from conversion of preforce-generating (A-M.ADP.Pi) states to force-bearing (A-M.ADP) states as the temperature is raised. A tension response to a simulated T-jump consists of three (one fast and two slow) components, but, by combining the two slow components, they could be reduced to two; their relative amplitudes vary with temperature. The model can qualitatively simulate features of the tension responses induced by large-T-jumps from low starting temperatures, and those induced by small-T-jumps from different starting temperatures and, also, the interactive effects of Pi and temperature on force in muscle fibres.
Related Links	http://dx.doi.org/10.1113/jphysiol.2005.090084
Ending Page	492
Page Count	22
Starting Page	471
File Format	PDF
ISSN	00223751
e-ISSN	14697793
Journal	The Journal of Physiology
Issue Number	Pt 2
Volume Number	567
Language	English
Publisher	Blackwell Science Inc
Publisher Date	2005-09-01
Access Restriction	Open
Rights Holder	Blackwell Science Inc
Subject Keyword	Physiology Research in Higher Education
Content Type	Text
Resource Type	Article
Subject	Physiology Sports Science

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Force generation examined by laser temperature-jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres

Cross-bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.

Temperature jump induced force generation in rabbit muscle fibres gets faster with shortening and shows a biphasic dependence on velocity

Effects of sarcomere length and temperature on the rate of ATP utilisation by rabbit psoas muscle fibres

Kinetics of force recovery following length changes in active skinned single fibres from rabbit psoas muscle

Transient tension changes initiated by laser temperature jumps in rabbit psoas muscle fibres.

Relaxation of rabbit psoas muscle fibres from rigor by photochemical generation of adenosine-5'-triphosphate.

Contractile activation and force generation in skinned rabbit muscle fibres: effects of hydrostatic pressure.

Temperature dependence of active tension in mammalian (rabbit psoas) muscle fibres: effect of inorganic phosphate

Endothermic force generation, temperature-jump experiments and effects of increased [MgADP] in rabbit psoas muscle fibres

Similar Documents

Force generation examined by laser temperature-jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres

Cross-bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.

Temperature jump induced force generation in rabbit muscle fibres gets faster with shortening and shows a biphasic dependence on velocity

Effects of sarcomere length and temperature on the rate of ATP utilisation by rabbit psoas muscle fibres

Kinetics of force recovery following length changes in active skinned single fibres from rabbit psoas muscle

Transient tension changes initiated by laser temperature jumps in rabbit psoas muscle fibres.

Relaxation of rabbit psoas muscle fibres from rigor by photochemical generation of adenosine-5'-triphosphate.

Contractile activation and force generation in skinned rabbit muscle fibres: effects of hydrostatic pressure.

Temperature dependence of active tension in mammalian (rabbit psoas) muscle fibres: effect of inorganic phosphate

Endothermic force generation, temperature-jump experiments and effects of increased [MgADP] in rabbit psoas muscle fibres