Putative ryanodine receptors in the sarcolemma of ventricular myocytes

The activity of caffeine-activated large conductance channels was recorded in whole-cell, patch-clamped, isolated ventricular myocytes from rabbit heart. The channels were permeable to monovalent and divalent cations and had a unitary monovalent cation conductance of 300-400 pS. Extracellular ruthen...

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Bibliographic Details
Published in:Pflügers Archiv 2000-05, Vol.440 (1), p.125-131
Main Authors: Kondo, R P, Weiss, J N, Goldhaber, J I
Format: Article
Language:English
Subjects:
Acetates - pharmacology
Animals
Caffeine - pharmacology
Calcium
Calcium - metabolism
Calcium - pharmacology
Cells, Cultured
Chelating Agents - pharmacology
Cytoplasm - metabolism
Ethylenediamines - pharmacology
Heart Ventricles - cytology
Heart Ventricles - metabolism
Ion Channels - drug effects
Ion Channels - metabolism
Meglumine - metabolism
Meglumine - pharmacology
Membrane Potentials - drug effects
Muscular system
Myocardium - cytology
Myocardium - metabolism
Patch-Clamp Techniques
Rabbits
Ruthenium Red - pharmacology
Ryanodine - pharmacology
Ryanodine Receptor Calcium Release Channel - drug effects
Ryanodine Receptor Calcium Release Channel - metabolism
Sarcolemma - metabolism
Sodium - metabolism
Substrate Specificity
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Summary:The activity of caffeine-activated large conductance channels was recorded in whole-cell, patch-clamped, isolated ventricular myocytes from rabbit heart. The channels were permeable to monovalent and divalent cations and had a unitary monovalent cation conductance of 300-400 pS. Extracellular ruthenium red reduced the unitary conductance of the caffeine-activated channel in a concentration- and voltage-dependent manner. Ryanodine locked the caffeine-activated channels into a subconductance state. Elevating intracellular Ca2+ by photolysis of "caged calcium" increased the number of channel openings. The properties of this caffeine-activated channel were remarkably similar to those of cardiac ryanodine receptors (RyR) and support the novel finding that these channels may also be found on the sarcolemmal membrane.
ISSN:0031-6768
1432-2013
DOI:10.1007/s004240000259