Protein kinase A-dependent activation of inward rectifier potassium channels by adenosine in rabbit coronary smooth muscle cells
- Authors
- Son, Youn Kyoung; Park, Won Sun; Ko, Jae-Hong; Han, Jin; Kim, Nari; Earm, Yung E.
- Issue Date
- Dec-2005
- Publisher
- Academic Press
- Keywords
- Adenosine; Inward rectifier K+ channel; Protein kinase C; Coronary artery
- Citation
- Biochemical and Biophysical Research Communications, v.337, no.4, pp 1145 - 1152
- Pages
- 8
- Journal Title
- Biochemical and Biophysical Research Communications
- Volume
- 337
- Number
- 4
- Start Page
- 1145
- End Page
- 1152
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/66785
- DOI
- 10.1016/j.bbrc.2005.09.176
- ISSN
- 0006-291X
1090-2104
- Abstract
- We studied the effect of adenosine on the Ba2+-sensitive K IR channels in the smooth muscle cells isolated from the small-diameter (<100 μm) coronary arteries of rabbit. Adenosine increased KIR currents in concentration-dependent manner (EC50 = 9.4 ± 1.4 μM, maximum increase of 153%). The adenosine-induced stimulation of KIR current was blocked by adenylyl cyclase inhibitor, SQ22536 and was mimicked by adenylyl cyclase activator, forskolin. The adenosine-induced increase of current was blocked by cyclic AMP-dependent protein kinase (PKA) inhibitors, KT 5720 and Rp-8-CPT-cAMPs. The adenosine-induced increase of KIR currents was blocked by an A 3-selective antagonist MRS1334, while the antagonists of other subtypes (DPCPX for A1, ZM241385 for A2A, and alloxazine for A2B) were all ineffective. Furthermore, an A3- selective agonist, 2-Cl-IB-MECA induced increase of KIR currents. We also examined the effect of adenosine on coronary blood flow (CBF) rate by using the Langendorff-perfused heart. In the presence of glibenclamide to exclude the effects of ATP-sensitive K+ (KATP) channels, CBF was increased by adenosine (10 μM), which was blocked by the addition of Ba 2+ (50 μM). Above results suggest that adenosine increases K IR current via A3 subtype through the activation of PKA in rabbit small-diameter coronary arterial smooth muscle cells. © 2005 Elsevier Inc. All rights reserved.
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