Role of receptor kinase in short-term desensitization of cardiac muscarinic K+ channels expressed in Chinese hamster ovary cells.
1. The cardiac muscarinic receptor-K+ channel system was reconstructed in Chinese hamster ovary (CHO) cells by transfecting the cells with the various components of the system. The activity of the muscarinic K+ channel was measured with the cell-attached configuration of the patch clamp technique. 2. In CHO cells transfected with the channel (Kir3.1/Kir3.4), receptor (hm2) and receptor kinase (GRK2), on exposure to agonist, there was a decline in channel activity as a result of desensitization, similar to that in atrial cells. 3. Whereas the desensitization was almost abolished by not transfecting with the receptor kinase or by transfecting with a mutant receptor lacking phosphorylation sites, it was only reduced (by approximately 39%) by transfecting with a mutant receptor kinase with little/kinase activity. 4. These results suggest that the receptor kinase is responsible for desensitization of the muscarinic K+ channel and that this involves phosphorylation-dependent and -independent mechanisms.
Shui
Z
Z
Department of Physiology, University of Leeds, UK.
Khan
I A
IA
Tsuga
H
H
Haga
T
T
Boyett
M R
MR
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004558:Electric Stimulation; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000166:cytology; D008564:Membrane Potentials / Q000502:physiology; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014162:Transfection
D018727:Muscarinic Antagonists; D026902:Potassium Channel Blockers; D011976:Receptors, Muscarinic; D020794:Receptor Protein-Tyrosine Kinases