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Calcium-independent K(+)-selective channel from chromaffin granule membranes.
- Source :
-
The Journal of membrane biology [J Membr Biol] 1992 Nov; Vol. 130 (2), pp. 191-202. - Publication Year :
- 1992
-
Abstract
- Intact adrenal chromaffin granules and purified granule membrane ghosts were allowed to fuse with acidic phospholipid planar bilayer membranes in the presence of Ca2+ (1 mM). From both preparations, we were able to detect a large conductance potassium channel (ca. 160 pS in symmetrical 400 mM K+), which was highly selective for K+ over Na+ (PK/PNa = 11) as estimated from the reversal potential of the channel current. Channel activity was unaffected by charybdotoxin, a blocker of the [Ca2+]-activated K+ channel of large conductance. Furthermore, this channel proved quite different from the previously described channels from other types of secretory vesicle preparations, not only in its selectivity and conductance, but also in its insensitivity to both calcium and potential across the bilayer. We conclude that the chromaffin granule membrane contains a K(+)-selective channel with large conductance. We suggest that the role of this channel may include ion movement during granule assembly or recycling, and do not rule out events leading to exocytosis.
- Subjects :
- Adrenal Medulla chemistry
Adrenal Medulla ultrastructure
Animals
Catecholamines metabolism
Cattle
Cell Fractionation
Charybdotoxin
Chromaffin Granules chemistry
Chromaffin Granules physiology
Exocytosis physiology
Intracellular Membranes physiology
Intracellular Membranes ultrastructure
Membrane Potentials physiology
Potassium Channels drug effects
Potassium Channels physiology
Scorpion Venoms pharmacology
Sodium pharmacology
Calcium physiology
Chromaffin Granules ultrastructure
Intracellular Membranes chemistry
Potassium Channels ultrastructure
Subjects
Details
- Language :
- English
- ISSN :
- 0022-2631
- Volume :
- 130
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- The Journal of membrane biology
- Publication Type :
- Academic Journal
- Accession number :
- 1283986
- Full Text :
- https://doi.org/10.1007/BF00231896