Effects of extracellular K+ and Ca2+ on membrane potential, contraction and 86Rb+ efflux in guinea-pig mesotubarium
(1990) In Pflügers Archiv 415(6). p.664-670- Abstract
- The effects of varying extracellular concentrations of K+ and Ca2+ [K+]o and [Ca2+]o on force development and membrane potential were investigated in the guinea-pig mesotubarium. At [K+]o up to 40 mM, spontaneous action potentials were present, while higher [K+]o gave sustained contractures at a stable membrane potential (-24 to -12 mV for [K+]o from 60 to 120 mM). Tension decreased successively with increasing [K+]o from 30 to 120 mM. The relaxing potency of the dihydropyridine Ca2+ antagonist, felodipine, increased as the membrane was depolarized with increasing [K+]o and action potentials ceased. These results are compatible with the existence of Ca2+ channels showing voltage-dependent affinity with dihydrophyridines. Increasing [Ca2+]o... (More)
- The effects of varying extracellular concentrations of K+ and Ca2+ [K+]o and [Ca2+]o on force development and membrane potential were investigated in the guinea-pig mesotubarium. At [K+]o up to 40 mM, spontaneous action potentials were present, while higher [K+]o gave sustained contractures at a stable membrane potential (-24 to -12 mV for [K+]o from 60 to 120 mM). Tension decreased successively with increasing [K+]o from 30 to 120 mM. The relaxing potency of the dihydropyridine Ca2+ antagonist, felodipine, increased as the membrane was depolarized with increasing [K+]o and action potentials ceased. These results are compatible with the existence of Ca2+ channels showing voltage-dependent affinity with dihydrophyridines. Increasing [Ca2+]o from 2.5 to 10 mM caused membrane hyperpolarization by about 11 mV and was accompanied by a lower frequency of spontaneous contractions and a longer duration of the relaxation between contractions. 86Rb+ efflux measurements in 60 mM K+ in the absence and presence of felodipine revealed a Ca2(+)-dependent component of the voltage-activated efflux. In normal solution (5.9 mM K+), efflux in the presence of felodipine was similar to the minimal value during normal spontaneous activity. The results indicate regulation of the permeability of K+ channels by the intracellular Ca2+ concentration ([Ca2+]i) and suggest participation of such channels in the generation of the regularly occurring bursts of action potentials characteristic of spontaneous activity in the mesotubarium. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1105285
- author
- Lydrup, M L and Hellstrand, Per LU
- organization
- publishing date
- 1990
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Smooth muscle, Ion channels, Calcium, Potassium, Calcium antagonists, Contraction, Electrophysiology
- in
- Pflügers Archiv
- volume
- 415
- issue
- 6
- pages
- 664 - 670
- publisher
- Springer
- external identifiers
-
- pmid:2336345
- scopus:0025217284
- ISSN
- 0031-6768
- DOI
- 10.1007/BF02584003
- language
- English
- LU publication?
- yes
- id
- 05ffebe3-123a-440e-b28d-bab8a09e8f41 (old id 1105285)
- date added to LUP
- 2016-04-01 16:16:40
- date last changed
- 2021-01-03 05:03:35
@article{05ffebe3-123a-440e-b28d-bab8a09e8f41,
abstract = {{The effects of varying extracellular concentrations of K+ and Ca2+ [K+]o and [Ca2+]o on force development and membrane potential were investigated in the guinea-pig mesotubarium. At [K+]o up to 40 mM, spontaneous action potentials were present, while higher [K+]o gave sustained contractures at a stable membrane potential (-24 to -12 mV for [K+]o from 60 to 120 mM). Tension decreased successively with increasing [K+]o from 30 to 120 mM. The relaxing potency of the dihydropyridine Ca2+ antagonist, felodipine, increased as the membrane was depolarized with increasing [K+]o and action potentials ceased. These results are compatible with the existence of Ca2+ channels showing voltage-dependent affinity with dihydrophyridines. Increasing [Ca2+]o from 2.5 to 10 mM caused membrane hyperpolarization by about 11 mV and was accompanied by a lower frequency of spontaneous contractions and a longer duration of the relaxation between contractions. 86Rb+ efflux measurements in 60 mM K+ in the absence and presence of felodipine revealed a Ca2(+)-dependent component of the voltage-activated efflux. In normal solution (5.9 mM K+), efflux in the presence of felodipine was similar to the minimal value during normal spontaneous activity. The results indicate regulation of the permeability of K+ channels by the intracellular Ca2+ concentration ([Ca2+]i) and suggest participation of such channels in the generation of the regularly occurring bursts of action potentials characteristic of spontaneous activity in the mesotubarium.}},
author = {{Lydrup, M L and Hellstrand, Per}},
issn = {{0031-6768}},
keywords = {{Smooth muscle; Ion channels; Calcium; Potassium; Calcium antagonists; Contraction; Electrophysiology}},
language = {{eng}},
number = {{6}},
pages = {{664--670}},
publisher = {{Springer}},
series = {{Pflügers Archiv}},
title = {{Effects of extracellular K+ and Ca2+ on membrane potential, contraction and 86Rb+ efflux in guinea-pig mesotubarium}},
url = {{http://dx.doi.org/10.1007/BF02584003}},
doi = {{10.1007/BF02584003}},
volume = {{415}},
year = {{1990}},
}