Electrophysiological characterization of ractk1 k+ channel in
stable cell line.
Suzuki, Makoto, Mitsunobu Murata, Masato Ikeda, Taku Miyoshi, Masashi
Imai.
Department of Pharmacology, Jichi Medical School. 3311-1,
Yakushiji, Minamikawachi, Tochigi 293-04, Japan
APStracts 3:0015C, 1996.
RACTK1 is a pH-sensitive K+ channel cloned from rabbit renal
collecting tubule cells. To characterize the function of this K+
channel more in detail, RACTK1 was transfected to an established cell
line and the patch clamp study was performed. cDNA of RACTK1 was
inserted in pMAM vector and transfected to Chinese Hamster Ovary
cells. In one out of 36 cell lines, the channel protein was expressed
by the dexamethasone-induced mRNA, and was detected by the specific
antibody. The RACTK1 K+ channel with 80 pS was consistently observed.
In inside-out patch, Ca2+ at the concentration higher than 500 nM
activated the channel. Open probability was decreased by protein
kinase A, (Po, from 45 to 4.2 %, n=6), but not by protein kinase C.
Whole cell currents of the transformed cells represented K+
conductance which was not blocked by an addition of charybdotoxin but
by apamin. RACTK1 K+ channel has similar, though not identical,
characteristics of Ca2+-activated K+ channel. RACTK1 might therefore
encode a subunit of intermediate conductance Ca2+-activated K+
channel observed in the apical membrane of rabbit renal collecting
duct.
Received 24 October 1995; accepted in final form 21 December
1995.
APS Manuscript Number C647-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96