Dissociation of phosphorylase a activation and contractile activity in rat portal vein
(1984) In Acta Physiologica Scandinavica 121(1). p.23-30- Abstract
- Isometric force, glycogen phosphorylase activity and lactate production were measured under conditions known to alter intracellular Ca2+ and cAMP to assess the role of these messengers in the coordination of metabolism with contractility in rat portal vein. Total phosphorylase (a + b) activity, was independent of treatment. The activity ratio phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on or high-K+ medium, and 0.57 after 20 min treatment with 10(-5) M isoproterenol + 10(-4) M papaverine. Under both of these conditions the muscle was totally relaxed. The phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on extracellular Ca2+, both in normal and... (More)
- Isometric force, glycogen phosphorylase activity and lactate production were measured under conditions known to alter intracellular Ca2+ and cAMP to assess the role of these messengers in the coordination of metabolism with contractility in rat portal vein. Total phosphorylase (a + b) activity, was independent of treatment. The activity ratio phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on or high-K+ medium, and 0.57 after 20 min treatment with 10(-5) M isoproterenol + 10(-4) M papaverine. Under both of these conditions the muscle was totally relaxed. The phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on extracellular Ca2+, both in normal and depolarizing medium. This suggests a lower Ca2+ sensitivity of the contractile than the phosphorylase system under these conditions, known to be associated with raised intracellular cAMP. During spontaneous activity and high-K+ induced contractures phosphorylase activity was increased compared to the relaxed state in Ca2+-free medium. A high level of phosphorylase activity (0.48) was elicited by the addition of 300 mM sucrose, which induces a contracture in Ca2+-free medium. Lactate production was in general parallel to phosphorylase activity, except for a relative increase in anoxia. The results suggest that in the intact cell the Ca2+-mediated linkage of contraction and phosphorylase may be modified by cAMP changing the Ca2+ sensitivities of the two systems in opposite directions. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1103284
- author
- Paul, R J and Hellstrand, Per LU
- organization
- publishing date
- 1984
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Acta Physiologica Scandinavica
- volume
- 121
- issue
- 1
- pages
- 23 - 30
- publisher
- Wiley-Blackwell
- external identifiers
-
- pmid:6331075
- scopus:0021142695
- ISSN
- 0001-6772
- language
- English
- LU publication?
- yes
- id
- 73cc0bc1-0eb8-4d37-85d3-3afd3925a42a (old id 1103284)
- date added to LUP
- 2016-04-01 16:34:34
- date last changed
- 2021-01-03 09:27:07
@article{73cc0bc1-0eb8-4d37-85d3-3afd3925a42a,
abstract = {{Isometric force, glycogen phosphorylase activity and lactate production were measured under conditions known to alter intracellular Ca2+ and cAMP to assess the role of these messengers in the coordination of metabolism with contractility in rat portal vein. Total phosphorylase (a + b) activity, was independent of treatment. The activity ratio phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on or high-K+ medium, and 0.57 after 20 min treatment with 10(-5) M isoproterenol + 10(-4) M papaverine. Under both of these conditions the muscle was totally relaxed. The phosphorylase activity ratio in the presence of isoproterenol and papaverine was dependent on extracellular Ca2+, both in normal and depolarizing medium. This suggests a lower Ca2+ sensitivity of the contractile than the phosphorylase system under these conditions, known to be associated with raised intracellular cAMP. During spontaneous activity and high-K+ induced contractures phosphorylase activity was increased compared to the relaxed state in Ca2+-free medium. A high level of phosphorylase activity (0.48) was elicited by the addition of 300 mM sucrose, which induces a contracture in Ca2+-free medium. Lactate production was in general parallel to phosphorylase activity, except for a relative increase in anoxia. The results suggest that in the intact cell the Ca2+-mediated linkage of contraction and phosphorylase may be modified by cAMP changing the Ca2+ sensitivities of the two systems in opposite directions.}},
author = {{Paul, R J and Hellstrand, Per}},
issn = {{0001-6772}},
language = {{eng}},
number = {{1}},
pages = {{23--30}},
publisher = {{Wiley-Blackwell}},
series = {{Acta Physiologica Scandinavica}},
title = {{Dissociation of phosphorylase a activation and contractile activity in rat portal vein}},
volume = {{121}},
year = {{1984}},
}