Characterization of inwardly rectifying K(+) conductance across the basolateral membrane of rat tracheal epithelia.
The rat primary cultured-airway monolayer has been an excellent model for deciphering the ion channel after nystatin permeabilization of its basolateral or apical membrane. Inwardly rectifying K(+) currents were characterized across the basolateral membrane in symmetrical HCO(-)(3)-free high K(+) Ringer's solution (125 mM) in this study. The potency of K(+) channel inhibitors against K(+) conductance was Ba(2+) (IC(50) = 5 microM) > Cs(+) (IC(50) = 2 mM) >> glybenclamide (IC(50) > 5 mM) >> TEA (IC(50) >> 100 mM). The application of basolateral Cs(+) changed K(+) conductance into an oscillating current, and its frequency (holding voltage = -100 mV) increased with increase in concentration of basolateral Cs(+) (0.05-5 mM) and in degree of hyperpolarization. Addition of basolateral Cs(+) blocked inward current strongly at -100 mV and hardly at all at -60 mV, giving a sharp curvature to the I-V relation of the IRK current. RT-PCR, Western blotting, and immunohistochemical analyses showed that Kir2.1 might be present in basolateral membrane of tracheal epithelia and plasma membrane of pulmonary alveolar cells.
Jeong
J S
JS
Department of Pathology, Dong-A Medical College, Busan, 602-103, South Korea.
Lee
H J
HJ
Jung
J S
JS
Shin
S H
SH
Son
Y J
YJ
Yoon
J H
JH
Lee
S H
SH
Lee
H S
HS
Yun
I
I
Hwang
T H
TH
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002463:Cell Membrane Permeability; D016764:Cell Polarity; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004553:Electric Conductivity; D006801:Humans; D007150:Immunohistochemistry; D015640:Ion Channel Gating / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D009297:Nasal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012137:Respiratory System / Q000166:cytology / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011188:Potassium; D002118:Calcium