Distinct effects of subcellular glycogen localization on tetanic relaxation time and endurance in mechanically skinned rat skeletal muscle fibres

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Udgivelsesdato: Jul-15
OriginalsprogEngelsk
TidsskriftJournal of Physiology
Vol/bind587
Udgave nummerPt 14
Sider (fra-til)3679-90
Antal sider11
ISSN0022-3751
DOI
StatusUdgivet - 15. jul. 2009

Fingeraftryk

Muscles
Transmission Electron Microscopy
Skeletal Muscle
Population
In Vitro Techniques

Citer dette

@article{0f6814e07aa711de9c46000ea68e967b,
title = "Distinct effects of subcellular glycogen localization on tetanic relaxation time and endurance in mechanically skinned rat skeletal muscle fibres",
abstract = "In vitro experiments indicate a non-metabolic role of muscle glycogen in contracting skeletal muscles. Since the sequence of events in excitation\#8211;contraction (E\#8211;C) coupling is known to be located close to glycogen granules, at specific sites on the fibre, we hypothesized that the distinct compartments of glycogen have specific effects on muscle fibre contractility and fatigability. Single skeletal muscle fibres (n = 19) from fed and fasted rats were mechanically skinned and divided into two segments. In one segment glycogen localization and volume fraction were estimated by transmission electron microscopy. The other segment was mechanically skinned and, in the presence of high and constant myoplasmic ATP and PCr, electrically stimulated (10 Hz, 0.8 s every 3 s) eliciting repeated tetanic contractions until the force response was decreased by 50{\%} (mean +/- S.E.M., 81 +/- 16, range 22-252 contractions). Initially the total myofibrillar glycogen volume percentage was 0.46 +/- 0.07{\%}, with 72 +/- 3{\%} in the intermyofibrillar space and 28 +/- 3{\%} in the intramyofibrillar space. The intramyofibrillar glycogen content was positively correlated with the fatigue resistance capacity (r(2) = 0.32, P = 0.02). Intermyofibrillar glycogen was inversely correlated with the half-relaxation time in the unfatigued tetanus (r(2) = 0.25, P = 0.03). These results demonstrate for the first time that two distinct subcellular populations of glycogen have different roles in contracting single muscle fibres under conditions of high myoplasmic ATP.",
keywords = "Skeletal muscle, Glycogen, Transmission Electron Microscopy",
author = "Joachim Nielsen and Schr{\o}der, {H D} and Rix, {C G} and Niels {\O}rtenblad",
year = "2009",
month = "7",
day = "15",
doi = "10.1113/jphysiol.2009.174862",
language = "English",
volume = "587",
pages = "3679--90",
journal = "Journal of Physiology",
issn = "0022-3751",
publisher = "Wiley-Blackwell",
number = "Pt 14",

}

Distinct effects of subcellular glycogen localization on tetanic relaxation time and endurance in mechanically skinned rat skeletal muscle fibres. / Nielsen, Joachim; Schrøder, H D; Rix, C G; Ørtenblad, Niels.

I: Journal of Physiology, Bind 587, Nr. Pt 14, 15.07.2009, s. 3679-90.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Distinct effects of subcellular glycogen localization on tetanic relaxation time and endurance in mechanically skinned rat skeletal muscle fibres

AU - Nielsen, Joachim

AU - Schrøder, H D

AU - Rix, C G

AU - Ørtenblad, Niels

PY - 2009/7/15

Y1 - 2009/7/15

N2 - In vitro experiments indicate a non-metabolic role of muscle glycogen in contracting skeletal muscles. Since the sequence of events in excitation\#8211;contraction (E\#8211;C) coupling is known to be located close to glycogen granules, at specific sites on the fibre, we hypothesized that the distinct compartments of glycogen have specific effects on muscle fibre contractility and fatigability. Single skeletal muscle fibres (n = 19) from fed and fasted rats were mechanically skinned and divided into two segments. In one segment glycogen localization and volume fraction were estimated by transmission electron microscopy. The other segment was mechanically skinned and, in the presence of high and constant myoplasmic ATP and PCr, electrically stimulated (10 Hz, 0.8 s every 3 s) eliciting repeated tetanic contractions until the force response was decreased by 50% (mean +/- S.E.M., 81 +/- 16, range 22-252 contractions). Initially the total myofibrillar glycogen volume percentage was 0.46 +/- 0.07%, with 72 +/- 3% in the intermyofibrillar space and 28 +/- 3% in the intramyofibrillar space. The intramyofibrillar glycogen content was positively correlated with the fatigue resistance capacity (r(2) = 0.32, P = 0.02). Intermyofibrillar glycogen was inversely correlated with the half-relaxation time in the unfatigued tetanus (r(2) = 0.25, P = 0.03). These results demonstrate for the first time that two distinct subcellular populations of glycogen have different roles in contracting single muscle fibres under conditions of high myoplasmic ATP.

AB - In vitro experiments indicate a non-metabolic role of muscle glycogen in contracting skeletal muscles. Since the sequence of events in excitation\#8211;contraction (E\#8211;C) coupling is known to be located close to glycogen granules, at specific sites on the fibre, we hypothesized that the distinct compartments of glycogen have specific effects on muscle fibre contractility and fatigability. Single skeletal muscle fibres (n = 19) from fed and fasted rats were mechanically skinned and divided into two segments. In one segment glycogen localization and volume fraction were estimated by transmission electron microscopy. The other segment was mechanically skinned and, in the presence of high and constant myoplasmic ATP and PCr, electrically stimulated (10 Hz, 0.8 s every 3 s) eliciting repeated tetanic contractions until the force response was decreased by 50% (mean +/- S.E.M., 81 +/- 16, range 22-252 contractions). Initially the total myofibrillar glycogen volume percentage was 0.46 +/- 0.07%, with 72 +/- 3% in the intermyofibrillar space and 28 +/- 3% in the intramyofibrillar space. The intramyofibrillar glycogen content was positively correlated with the fatigue resistance capacity (r(2) = 0.32, P = 0.02). Intermyofibrillar glycogen was inversely correlated with the half-relaxation time in the unfatigued tetanus (r(2) = 0.25, P = 0.03). These results demonstrate for the first time that two distinct subcellular populations of glycogen have different roles in contracting single muscle fibres under conditions of high myoplasmic ATP.

KW - Skeletal muscle

KW - Glycogen

KW - Transmission Electron Microscopy

U2 - 10.1113/jphysiol.2009.174862

DO - 10.1113/jphysiol.2009.174862

M3 - Journal article

C2 - 19470780

VL - 587

SP - 3679

EP - 3690

JO - Journal of Physiology

JF - Journal of Physiology

SN - 0022-3751

IS - Pt 14

ER -