Ca2 -activated K Currents of Pancreatic Duct Cells in Guinea-pig.
- Author:
Han Wook LEE
1
;
Jingchao LI
;
Na Youn KOO
;
Zheng Gen PIAO
;
Sung Min HWANG
;
Jae Woong HAN
;
Han Saem CHOI
;
Jong Heun LEE
;
Joong Soo KIM
;
Kyungpyo PARK
Author Information
1. Department of Physiology, College of Dentistry, Seoul National University and Dental Research Institute, Seoul, Korea. kppark@snu.ac.kr
- Publication Type:Original Article
- Keywords:
Duct cells;
Guinea pig;
Pancreas;
K currents;
Ca2
- MeSH:
Animals;
Baths;
Exocrine Glands;
Guinea Pigs;
Membrane Potentials;
Pancreas;
Pancreatic Ducts*;
Recycling;
Secretory Pathway;
Tea
- From:The Korean Journal of Physiology and Pharmacology
2004;8(6):335-338
- CountryRepublic of Korea
- Language:English
-
Abstract:
There are numerous studies on transepithelial transports in duct cells including Cl and/or HCO3. However, studies on transepithelial K transport of normal duct cells in exocrine glands are scarce. In the present study, we examined the characteristics of K currents in single duct cells isolated from guinea pig pancreas, using a whole-cell patch clamp technique. Both Cl and K conductance were found with KCl rich pipette solutions. When the bath solution was changed to low Cl, reversal potentials shifted to the negative side, 75 4 mV, suggesting that this current is dominantly selective to K. We then characterized this outward rectifying K current and examined its Ca2 dependency. The K currents were activated by intracellular Ca2. 100 nM or 500 nM Ca2 in pipette significantly (P< 0.05) increased outward currents (currents were normalized, 76.8 7.9 pA, n=4 or 107.9 35.5 pA, n=6) at 100 mV membrane potential, compared to those with 0 nM Ca2 in pipette (27.8 3.7 pA, n=6). We next examined whether this K current, recorded with 100 nM Ca2 in pipette, was inhibited by various inhibitors, including Ba2, TEA and iberiotoxin. The currents were inhibited by 40.4 % (n=3), 87.0 % (n=5) and 82.5 % (n=9) by 1 mM Ba2, 5 mM TEA and 100 nM iberiotoxin, respectively. Particularly, an almost complete inhibition of the current by 100 nM iberiotoxin further confirmed that this current was activated by intracellular Ca2. The K current may play a role in secretory process, since recycling of K is critical for the initiation and sustaining of Cl or HCO3 secretion in these cells.
