ATP-sensitive K(+) channels composed of Kir6.1 and SUR2B subunits in guinea pig gastric myocytes.
This study was designed to identify the single-channel properties and molecular entity of ATP-sensitive K(+) (K(ATP)) channels in guinea pig gastric myocytes with patch-clamp recording and RT-PCR. Pinacidil and diazoxide activated K(ATP) currents in a glibenclamide-sensitive manner. The open probability of channels was enhanced by the application of 10 microM pinacidil from 0.085 +/- 0.04 to 0.20 +/- 0.05 (n = 7) and was completely blocked by 10 microM glibenclamide. Single-channel conductance was 37.3 +/- 2.5 pS (n = 4) between -80 and -20 mV in symmetrical K(+) gradient conditions. In inside-out mode, K(ATP) channels showed no spontaneous openings and were activated by the application of nucleotide diphosphates to the cytoplasmic side. These single-channel properties are similar to those of the nucleotide diphosphate-dependent K(+) channels in vascular smooth muscle, which are composed of Kir6.1 and sulfonylurea receptor (SUR)2B. RT-PCR demonstrated the presence of Kir6.1, Kir6.2, and SUR2B in guinea pig stomach smooth muscle cells. These results suggest that K(ATP) channels in smooth muscle cells of the guinea pig stomach are composed of Kir6.1 and SUR2B.
Sim
Jae Hoon
JH
Department of Physiology and Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea.
Yang
Dong K
DK
Kim
Young Chul
YC
Park
Sung Jin
SJ
Kang
Tong Mook
TM
So
Insuk
I
Kim
Ki Whan
KW
D018528:ATP-Binding Cassette Transporters; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D020110:Pinacidil / Q000494:pharmacology; D011188:Potassium / Q000493:pharmacokinetics; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug / Q000235:genetics* / Q000378:metabolism; D013270:Stomach / Q000166:cytology / Q000502:physiology*; D064233:Sulfonylurea Receptors; D014665:Vasodilator Agents / Q000494:pharmacology
D018528:ATP-Binding Cassette Transporters; D000889:Anti-Arrhythmia Agents; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D014665:Vasodilator Agents; D000244:Adenosine Diphosphate; D020110:Pinacidil; D000255:Adenosine Triphosphate; D011188:Potassium; D005905:Glyburide; D002118:Calcium