Modulation of the muscarinic K+ channel by P2-purinoceptors in guinea-pig atrial myocytes

The Journal of Physiology
H Matsuura, T Ehara

Abstract

1. Activation of muscarinic K+ (KACh) channels by P2-purinergic agonists, such as ATP, decreases monotonically in the continued presence of agonist. We investigated the mechanisms underlying this process of decline in guinea-pig atrial myocytes using the patch-clamp technique. 2. External ATP reversibly depressed the acetylcholine (ACh, 5.5-11 microM)-induced KACh current in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of 5.4 microM. 3. External ATP irreversibly reduced guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S)-induced KACh current both in control and pertussis toxin (PTX)-pretreated cells, suggesting (i) that the ATP-induced inhibition of KACh current occurred at some step(s) downstream from the activation of the PTX-sensitive G protein, GK, and (ii) that a PTX-insensitive G protein was involved in the signal transduction pathway. 4. The potency order of ATP analogues in reducing KACh current was ATP > or = 2-methylthio-ATP > or = alpha, beta-methylene-ATP, indicating involvement of a P2Y-type purinoceptor. 5. In the cell-attached patch recording, ATP (100 microM) applied to the bath solution reduced the activity of the KACh channels activated by ACh in the pipette, in two out of...Continue Reading

Citations

Feb 15, 2008·Naunyn-Schmiedeberg's Archives of Pharmacology·Laszlo KölesPeter Illes
Sep 13, 2003·British Journal of Pharmacology·Jonathan W BowlerAnnmarie Surprenant
Jan 5, 1999·The Journal of General Physiology·S M Wilson, P A Pappone
Sep 15, 2004·The Journal of Biological Chemistry·Wei-Guang DingHiroshi Matsuura
Dec 23, 2009·Bulletin of Experimental Biology and Medicine·T A AnikinaA A Zverev
Mar 1, 2012·Pflügers Archiv : European journal of physiology·Jie WuMinoru Horie
Sep 27, 2003·Acta Physiologica Scandinavica·K A BaeC K Kim
Mar 29, 2001·Physiological Reviews·G Vassort

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