The Ca2+ and Mg2+ permeabilities of sarcoplasmic reticulum vesicles were measured by using a fluorescence chelate probe, chlortetracycline. The Mg2+ permeability was studied extensively. The data were analyzed under the assumption that the increment of fluorescence intensity is proportional to the amount of the divalent cations inside the vesicles. The validity of this assumption was confirmed by the tracer method with Ca2+. The presence of Ca2+ or Mg2+ had little effect on the Mg2+ efflux, but greatly affected the Ca2+ efflux. In the absence of extravesicular divalent cations, the permeabilities for Ca2+ and Mg2+ were almost the same, but the Ca2+ permeability was slightly reduced by the presence of Mg2+ and greatly reduced by Ca2+. In the absence of extravesicular divalent cations, the Ca2+ and Mg2+ permeabilities increased in parallel with increasing pH. For example, the permeation times for Mg2+ and Ca2+ were about 3 min at pH 6.5 and 20 s at pH 8.1 at room temperature. Kinetic analysis of the fluorescence change suggested the existence of two kinds of vesicles with different permeabilities.
Magnesium permeability of sarcoplasmic reticulum vesicles monitored in terms of chlortetracycline fluorescence. Publishing Authors By Initials
Magnesium permeability of sarcoplasmic reticulum vesicles monitored in terms of chlortetracycline fluorescence. Journal Published:
PUBLICATION TYPE: Journal Article
Journal: Journal of biochemistry
VOLUME: 87
Page Numbers: 709-16
Journal Abbreviation: J. Biochem.
ISSN: 0021-924X
DAY: 19
MONTH: Mar
YEAR: 1980
Magnesium permeability of sarcoplasmic reticulum vesicles monitored in terms of chlortetracycline fluorescence. Information
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LANGUAGE: eng
NlmUniqueID: 376600
Magnesium permeability of sarcoplasmic reticulum vesicles monitored in terms of chlortetracycline fluorescence. Keywords Mesh Terms:
KEYWORDS: Time Factors
MESH TERMS: metabolism
Chemical & Substance for Abstract: Magnesium permeability of sarcoplasmic reticulum vesicles monitored in terms of chlortetracycline fluorescence. Information
Substance Name: Calcium
Registry Number: 7440-70-2
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Country: JAPAN
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MEDLINETA: J Biochem
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