Abstract |
Calcium conducting channels were studied in blebs of sarcoplasmic reticulum described by Stein & Palade (1988). The calcium channels had at least three conductance states (70 pS, 50 pS and 37 pS) and were weakly selective for calcium ions, with a permeability ratio Ca2+ to K+ of about 3.4. The open probability of the channel was strongly voltage dependent, decreasing at positive membrane voltages. 10 microM ryanodine and 5 microM ruthenium red had no effect on this channel; neither did millimolar concentrations of ATP, Mg2+, caffeine, and Ca2+, implying that the calcium conducting channels are not ryanodine receptors. Several calcium pump inhibitors--namely, vanadate, AlF4-, reactive red 120, and cyclopiazonic acid--had obvious effects on the calcium conducting channels, suggesting that the calcium conducting channel of SR membrane blebs is some form of the SR calcium pump.
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Authors | J Wang, J M Tang, R S Eisenberg |
Journal | The Journal of membrane biology
(J Membr Biol)
Vol. 130
Issue 2
Pg. 163-81
(Nov 1992)
ISSN: 0022-2631 [Print] United States |
PMID | 1283985
(Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
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Chemical References |
- Calcium Channels
- Indoles
- Potassium Channels
- Triazines
- Ruthenium Red
- Ryanodine
- Vanadates
- reactive red 120 dye
- Calcium-Transporting ATPases
- Magnesium
- Calcium
- cyclopiazonic acid
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Topics |
- Animals
- Calcium
(pharmacokinetics, pharmacology)
- Calcium Channels
(drug effects, physiology)
- Calcium-Transporting ATPases
(drug effects, physiology)
- Dose-Response Relationship, Drug
- Indoles
(pharmacology)
- Magnesium
(pharmacology)
- Potassium Channels
(drug effects, physiology)
- Rana catesbeiana
- Ruthenium Red
(pharmacology)
- Ryanodine
(pharmacology)
- Sarcoplasmic Reticulum
(chemistry, ultrastructure)
- Triazines
(pharmacology)
- Vanadates
(pharmacology)
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