Referenced in: none

Automatically associated channels: Kir2.1 , Kir2.4 , Kir3.1 , Kir3.4

Title: Evidence of involvement of GIRK1/GIRK4 in long-term desensitization of cardiac muscarinic K+ channels.

Authors: Z Shui, T T Yamanushi, M R Boyett

Journal, date & volume: Am. J. Physiol. Heart Circ. Physiol., 2001 Jun , 280, H2554-62

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11356610

Abstract
The cardiac M2 muscarinic receptor/G protein/K+ channel system was studied in neonatal rat atrial cells cultured with and without 10 microM carbachol (CCh) for 24 h. Channel activity in CCh-pretreated cells was substantially reduced as a result of long-term desensitization regardless of whether the channel was activated by ACh in cell-attached patches or GTP in inside-out patches. Channel activity in CCh-pretreated cells was also low when the receptor was bypassed and the G protein and channel were directly activated by [gamma-S]GTP or both the receptor and G protein were bypassed and the channel was directly activated by trypsin. Finally, in CCh-pretreated cells, the whole cell K+ current was low when the channel was activated via the independent adenosine receptor. This suggests that the channel is involved in long-term desensitization. However, in CCh-pretreated cells, although the receptor was internalized, there was no internalization of the channel. We suggest that the function of the muscarinic K+ channel declines in long-term desensitization of the cardiac M2 muscarinic receptor/G protein/K+ channel system.