The forcevelocity relation in phasic contractions of venous smooth muscle
(1975) In Acta Physiologica Scandinavica 93(2). p.157166 Abstract
 The forcevelocity relation of the rat portal vein has been studied during regular spontaneous contractions induced by elevated levels of [K+]O AND [Ca2+]o. No satisfactory description of the forcevelocity relation was obtained by measuring shortening velocity in afterloaded isotonic contractions. Therefore the method of isotonic quick release was used, as this permits mechanical studies at specified instants of the contractionrelaxation cycle. The temporal development of the forcevelocity relation in the phasic response was investigated. During a time interval in the rising phase of the contraction, at about the time for maximal dP/dt, the forcevelicity curves were practically identical, suggesting a plateau in the intensity of... (More)
 The forcevelocity relation of the rat portal vein has been studied during regular spontaneous contractions induced by elevated levels of [K+]O AND [Ca2+]o. No satisfactory description of the forcevelocity relation was obtained by measuring shortening velocity in afterloaded isotonic contractions. Therefore the method of isotonic quick release was used, as this permits mechanical studies at specified instants of the contractionrelaxation cycle. The temporal development of the forcevelocity relation in the phasic response was investigated. During a time interval in the rising phase of the contraction, at about the time for maximal dP/dt, the forcevelicity curves were practically identical, suggesting a plateau in the intensity of active state. At later stages of the twitch the curves were progressively displaced towards the origin, the intercepts on both the force and the velocity axis becoming smaller. At the time of the isometric peak the maximal shortening velocity had declined relatively more than the isometric force. This is presumably caused by inhomogeneous activation of the muscle at the beginning of relaxation, The maximal forcevelocity relation in the rising phase of the contraction can be described by Hill's (1938) equation with the following parameters (at 37 degrees tc): a/Po = 0.73 plus or minus 0.04, b = 0.54 plus or minus 0.04 lengths/s, Vmax = 0.74 plus or minus 0.02 lengths/s (n = 7, mean plus or minus S.E,). The forcevelocity relation of the portal vein in comparison with other kinds of muscle is discussed. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/1102590
 author
 Hellstrand, Per ^{LU} and Johansson, B
 organization
 publishing date
 1975
 type
 Contribution to journal
 publication status
 published
 subject
 in
 Acta Physiologica Scandinavica
 volume
 93
 issue
 2
 pages
 157  166
 publisher
 WileyBlackwell
 external identifiers

 pmid:1146568
 scopus:0016733676
 ISSN
 00016772
 language
 English
 LU publication?
 yes
 id
 d400c175eb684204b944665623db4648 (old id 1102590)
 date added to LUP
 20160401 16:06:57
 date last changed
 20200112 19:02:58
@article{d400c175eb684204b944665623db4648, abstract = {The forcevelocity relation of the rat portal vein has been studied during regular spontaneous contractions induced by elevated levels of [K+]O AND [Ca2+]o. No satisfactory description of the forcevelocity relation was obtained by measuring shortening velocity in afterloaded isotonic contractions. Therefore the method of isotonic quick release was used, as this permits mechanical studies at specified instants of the contractionrelaxation cycle. The temporal development of the forcevelocity relation in the phasic response was investigated. During a time interval in the rising phase of the contraction, at about the time for maximal dP/dt, the forcevelicity curves were practically identical, suggesting a plateau in the intensity of active state. At later stages of the twitch the curves were progressively displaced towards the origin, the intercepts on both the force and the velocity axis becoming smaller. At the time of the isometric peak the maximal shortening velocity had declined relatively more than the isometric force. This is presumably caused by inhomogeneous activation of the muscle at the beginning of relaxation, The maximal forcevelocity relation in the rising phase of the contraction can be described by Hill's (1938) equation with the following parameters (at 37 degrees tc): a/Po = 0.73 plus or minus 0.04, b = 0.54 plus or minus 0.04 lengths/s, Vmax = 0.74 plus or minus 0.02 lengths/s (n = 7, mean plus or minus S.E,). The forcevelocity relation of the portal vein in comparison with other kinds of muscle is discussed.}, author = {Hellstrand, Per and Johansson, B}, issn = {00016772}, language = {eng}, number = {2}, pages = {157166}, publisher = {WileyBlackwell}, series = {Acta Physiologica Scandinavica}, title = {The forcevelocity relation in phasic contractions of venous smooth muscle}, volume = {93}, year = {1975}, }