Sodium-activated Potassium Current in Guinea pig Gastric Myocytes.
10.3346/jkms.2007.22.1.57
- Author:
Young Chul KIM
1
;
Jae Hoon SIM
;
Tong Mook KANG
;
Hikaru SUZUKI
;
Seung Ryul KIM
;
Seong Chun KWON
;
Wen Xie XU
;
Sang Jin LEE
;
Ki Whan KIM
Author Information
1. Department of Physiology, Chungbuk National University, College of Medicine, Cheongju, Korea. physiokyc@chungbuk.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Muscle, Smooth;
Myocytes, Smooth Muscle;
Gastrointestinal Tract;
Stomach;
Na+ -activated K+ Current (I(K(Na)));
Guinea Pigs
- MeSH:
Tetraethylammonium Compounds/pharmacology;
Stomach/*physiology;
Sodium/metabolism/*pharmacology;
Potassium Channels/*physiology;
Potassium Channel Blockers/pharmacology;
Myocytes, Smooth Muscle/*physiology;
Membrane Potentials;
Male;
Guinea Pigs;
Female;
Chlorides/pharmacology;
Calcium/metabolism;
Animals
- From:Journal of Korean Medical Science
2007;22(1):57-62
- CountryRepublic of Korea
- Language:English
-
Abstract:
This study was designed to identify and characterize Na+ -activated K+ current (I(K(Na))) in guinea pig gastric myocytes under whole-cell patch clamp. After whole-cell configuration was established under 110 mM intracellular Na+ concentration ([Na+]i) at holding potential of -60 mV, a large inward current was produced by external 60 mM K+([K+] degree). This inward current was not affected by removal of external Ca2+. K+ channel blockers had little effects on the current (p>0.05). Only TEA (5 mM) inhibited steady-state current to 68+/-2.7% of the control (p<0.05). In the presence of K+ channel blocker cocktail (mixture of Ba2+, glibenclamide, 4-AP, apamin, quinidine and TEA), a large inward current was activated. However, the amplitude of the steadystate current produced under [K+]degree (140 mM) was significantly smaller when Na+ in pipette solution was replaced with K+ - and Li+ in the presence of K+ channel blocker cocktail than under 110 mM [Na+]i. In the presence of K+ channel blocker cocktail under low Cl- pipette solution, this current was still activated and seemed K+ -selective, since reversal potentials (E(rev)) of various concentrations of [K+]degree-induced current in current/voltage (I/V) relationship were nearly identical to expected values. R-56865 (10-20 microgram), a blocker of IK(Na), completely and reversibly inhibited this current. The characteristics of the current coincide with those of IK(Na) of other cells. Our results indicate the presence of IK(Na) in guinea pig gastric myocytes.
