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Complete reversal of run-down in rabbit cardiac Ca2+ channels by patch-cramming in Xenopus oocytes; partial reversal by protein kinase A.
- Source :
- Pflügers Archiv: European Journal of Physiology; Apr1999, Vol. 437 Issue 6, p888-894, 7p
- Publication Year :
- 1999
-
Abstract
- The rabbit cardiac Ca<superscript>2+</superscript> channel (α<subscript>1C</subscript>) expressed in Xenopus oocytes exhibited a complete run-down of ionic currents when cell-attached patches were excised. The α<subscript>1C</subscript> channel was expressed alone or was coexpressed with the accessory β<subscript>2a</subscript> or β<subscript>1b</subscript> subunit. The catalytic subunit of protein kinase A (PKAc) and MgATP were capable of delaying the run-down of single-channel currents. In 33% of the α<subscript>1C</subscript> patches, and 26% of the α<subscript>1C</subscript>+β<subscript>2a</subscript> patches, inclusion of PKAc in the bath solution delayed the run-down for a maximum of 20 min. In experiments where PKAc in the bath was not sufficient to delay the run-down of channel activity, insertion of the patch back into the oocyte (patch-cramming) could restore channel activity. Gating currents were also measured in the α<subscript>1C</subscript>+β<subscript>1b</subscript> channel and were not subject to any run-down, even after the complete run-down of ionic currents. The results presented here reveal that PKAc is capable of delaying the run-down of currents in a subset of patches. The patch-cramming results suggest that a cytoplasmic factor, in addition to phosphorylation of the channel (by PKAc), may be involved in the maintenance of channel activity. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00316768
- Volume :
- 437
- Issue :
- 6
- Database :
- Complementary Index
- Journal :
- Pflügers Archiv: European Journal of Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 49981171
- Full Text :
- https://doi.org/10.1007/s004240050859