Paradoxical decrease in cytosolic calcium with increasing depolarization by potassium in guinea-pig mesotubarium smooth muscle
(1992) In Pflügers Archiv 420(5-6). p.428-433- Abstract
- The free intracellular Ca2+ concentration ([Ca2+]i) was measured simultaneously with isometric force in strips of guinea-pig mesotubarium using the Fura-2 technique. [Ca2+]i and force were maximal at a relatively low (30 mM) concentration of extracellular K+ ([K+]o), and declined at 90 and 140 mM K+. Plateau values of both [Ca2+]i and force were higher in the presence of 5.10(-6) M ryanodine, indicating that the sarcoplasmic reticulum (SR) contributes to the decline with depolarization. Force and [Ca2+]i at 90 mM K+ were both lower then the high-K+ solution was applied after a period in 30 mM K+ than after a period in normal solution (5.9 mM K+), consistent with inactivation of Ca2+ channels during prolonged depolarization. Addition of... (More)
- The free intracellular Ca2+ concentration ([Ca2+]i) was measured simultaneously with isometric force in strips of guinea-pig mesotubarium using the Fura-2 technique. [Ca2+]i and force were maximal at a relatively low (30 mM) concentration of extracellular K+ ([K+]o), and declined at 90 and 140 mM K+. Plateau values of both [Ca2+]i and force were higher in the presence of 5.10(-6) M ryanodine, indicating that the sarcoplasmic reticulum (SR) contributes to the decline with depolarization. Force and [Ca2+]i at 90 mM K+ were both lower then the high-K+ solution was applied after a period in 30 mM K+ than after a period in normal solution (5.9 mM K+), consistent with inactivation of Ca2+ channels during prolonged depolarization. Addition of carbachol to the depolarized muscle caused a maintained increase in force without maintained increase in [Ca2+]i. We conclude that the decrease in force at increased [K+]o (the "calcium-potassium paradox") is due to a membrane-potential-mediated decrease in [Ca2+]i and, to a lesser extent, to desensitization of the contractile-regulatory apparatus to Ca2+. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1106622
- author
- Lydrup, M L ; Himpens, B ; Droogmans, G ; Hellstrand, Per LU and Somlyo, A P
- organization
- publishing date
- 1992
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Calcium, Mesotubarium, Smooth muscle, Fura-2, K+ depolarization
- in
- Pflügers Archiv
- volume
- 420
- issue
- 5-6
- pages
- 428 - 433
- publisher
- Springer
- external identifiers
-
- pmid:1377377
- scopus:0026697081
- ISSN
- 0031-6768
- DOI
- 10.1007/BF00374616
- language
- English
- LU publication?
- yes
- id
- a828fe47-3869-4d2a-9e52-cf4280bdc038 (old id 1106622)
- date added to LUP
- 2016-04-01 17:05:09
- date last changed
- 2021-01-03 05:27:27
@article{a828fe47-3869-4d2a-9e52-cf4280bdc038,
abstract = {{The free intracellular Ca2+ concentration ([Ca2+]i) was measured simultaneously with isometric force in strips of guinea-pig mesotubarium using the Fura-2 technique. [Ca2+]i and force were maximal at a relatively low (30 mM) concentration of extracellular K+ ([K+]o), and declined at 90 and 140 mM K+. Plateau values of both [Ca2+]i and force were higher in the presence of 5.10(-6) M ryanodine, indicating that the sarcoplasmic reticulum (SR) contributes to the decline with depolarization. Force and [Ca2+]i at 90 mM K+ were both lower then the high-K+ solution was applied after a period in 30 mM K+ than after a period in normal solution (5.9 mM K+), consistent with inactivation of Ca2+ channels during prolonged depolarization. Addition of carbachol to the depolarized muscle caused a maintained increase in force without maintained increase in [Ca2+]i. We conclude that the decrease in force at increased [K+]o (the "calcium-potassium paradox") is due to a membrane-potential-mediated decrease in [Ca2+]i and, to a lesser extent, to desensitization of the contractile-regulatory apparatus to Ca2+.}},
author = {{Lydrup, M L and Himpens, B and Droogmans, G and Hellstrand, Per and Somlyo, A P}},
issn = {{0031-6768}},
keywords = {{Calcium; Mesotubarium; Smooth muscle; Fura-2; K+ depolarization}},
language = {{eng}},
number = {{5-6}},
pages = {{428--433}},
publisher = {{Springer}},
series = {{Pflügers Archiv}},
title = {{Paradoxical decrease in cytosolic calcium with increasing depolarization by potassium in guinea-pig mesotubarium smooth muscle}},
url = {{http://dx.doi.org/10.1007/BF00374616}},
doi = {{10.1007/BF00374616}},
volume = {{420}},
year = {{1992}},
}