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A mechanical stretch induces contractile activation in unstimulated developing rat skeletal muscle in vitro

Mutungi, G; Edman, Paul LU and Ranatunga, K W (2003) In Journal of Physiology 551(1). p.93-102
Abstract
The effects of a stretch-release cycle (25 of the resting muscle fibre length, Lo) on both tension and [Ca2+i in small, unstimulated, intact muscle fibre bundles isolated from adult and neonatal rats were investigated at 20 C. The results show that the effects of the length change depended on the age of the rats. Thus, the length change produced three effects in the neonatal rat muscle fibre bundles, but only a single effect in the adult ones. In the neonatal fibre bundles, the length change led to an increase in resting muscle tension and to a transient increase in [Ca2+i. The stretch-release cycle was then followed by a twitch-like tension response. In the adult fibre bundles, only the increase in resting tension was seen and both the... (More)
The effects of a stretch-release cycle (25 of the resting muscle fibre length, Lo) on both tension and [Ca2+i in small, unstimulated, intact muscle fibre bundles isolated from adult and neonatal rats were investigated at 20 C. The results show that the effects of the length change depended on the age of the rats. Thus, the length change produced three effects in the neonatal rat muscle fibre bundles, but only a single effect in the adult ones. In the neonatal fibre bundles, the length change led to an increase in resting muscle tension and to a transient increase in [Ca2+i. The stretch-release cycle was then followed by a twitch-like tension response. In the adult fibre bundles, only the increase in resting tension was seen and both the transient increase in [Ca2+i and the stretch-induced twitch-like tension response were absent. The amplitude of the twitch-like tension response was affected by both 2,3-butanedione monoxime and sarcomere length in the same manner as active twitch tension, suggesting that it arose from actively cycling crossbridges. It was also reversibly abolished by 25 mM K+, 1 M tetrodotoxin and 1.5 mM lidocaine (lignocaine), and was significantly depressed (P< 0.001) by lowering [Ca2+o. These findings suggest that a rapid stretch in neonatal rats induces a propagated impulse that leads to an increase in [Ca2+i, and that abolishing the action potential abolishes the stretch-induced twitch-like tension response. In 5- to 7-day-old rats, the twitch-like tension response was 50 of the isometric twitch. It then decreased progressively with age and was virtually absent by the time the rats were 21 days old. Interestingly, this is the same period over which rat muscles differentiate from their neonatal to their adult types. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physiology
volume
551
issue
1
pages
93 - 102
publisher
The Physiological Society
external identifiers
  • wos:000185247700011
  • pmid:12813148
  • scopus:0042856295
ISSN
1469-7793
DOI
10.1113/jphysiol.2003.044776
language
English
LU publication?
yes
id
a991c1bf-656c-4596-a024-612ad9373a35 (old id 131813)
date added to LUP
2007-07-18 11:25:24
date last changed
2018-01-07 09:33:57
@article{a991c1bf-656c-4596-a024-612ad9373a35,
  abstract     = {The effects of a stretch-release cycle (25 of the resting muscle fibre length, Lo) on both tension and [Ca2+i in small, unstimulated, intact muscle fibre bundles isolated from adult and neonatal rats were investigated at 20 C. The results show that the effects of the length change depended on the age of the rats. Thus, the length change produced three effects in the neonatal rat muscle fibre bundles, but only a single effect in the adult ones. In the neonatal fibre bundles, the length change led to an increase in resting muscle tension and to a transient increase in [Ca2+i. The stretch-release cycle was then followed by a twitch-like tension response. In the adult fibre bundles, only the increase in resting tension was seen and both the transient increase in [Ca2+i and the stretch-induced twitch-like tension response were absent. The amplitude of the twitch-like tension response was affected by both 2,3-butanedione monoxime and sarcomere length in the same manner as active twitch tension, suggesting that it arose from actively cycling crossbridges. It was also reversibly abolished by 25 mM K+, 1 M tetrodotoxin and 1.5 mM lidocaine (lignocaine), and was significantly depressed (P&lt; 0.001) by lowering [Ca2+o. These findings suggest that a rapid stretch in neonatal rats induces a propagated impulse that leads to an increase in [Ca2+i, and that abolishing the action potential abolishes the stretch-induced twitch-like tension response. In 5- to 7-day-old rats, the twitch-like tension response was 50 of the isometric twitch. It then decreased progressively with age and was virtually absent by the time the rats were 21 days old. Interestingly, this is the same period over which rat muscles differentiate from their neonatal to their adult types.},
  author       = {Mutungi, G and Edman, Paul and Ranatunga, K W},
  issn         = {1469-7793},
  language     = {eng},
  number       = {1},
  pages        = {93--102},
  publisher    = {The Physiological Society},
  series       = {Journal of Physiology},
  title        = {A mechanical stretch induces contractile activation in unstimulated developing rat skeletal muscle in vitro},
  url          = {http://dx.doi.org/10.1113/jphysiol.2003.044776},
  volume       = {551},
  year         = {2003},
}