Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> Currents of Pancreatic Duct Cells in Guinea-pig
Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> Currents of Pancreatic Duct Cells in Guinea-pig
- Han-Wook Lee Jingchao Li Na-Youn Koo Zheng Gen Piao Sung Min Hwang Jae-Woong Han Han-Saem Choi Jong-
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제8권 제6호
- 등재여부 : KCI등재
- 2004.01
- 335 - 338 (4 pages)
There are numerous studies on transepithelial transports in duct cells including Cl<SUP>⁣</SUP> and/or HCO<SUB>3</SUB><SUP>⁣</SUP>. However, studies on transepithelial K<SUP>⁢</SUP> transport of normal duct cells in exocrine glands are scarce. In the present study, we examined the characteristics of K<SUP>⁢</SUP> currents in single duct cells isolated from guinea pig pancreas, using a whole-cell patch clamp technique. Both Cl<SUP>⁣</SUP> and K<SUP>⁢</SUP> conductance were found with KCl rich pipette solutions. When the bath solution was changed to low Cl<SUP>⁣</SUP>, reversal potentials shifted to the negative side, ⁣75⁑4 mV, suggesting that this current is dominantly selective to K<SUP>⁢</SUP>. We then characterized this outward rectifying K<SUP>⁢</SUP> current and examined its Ca<SUP>2⁢</SUP> dependency. The K<SUP>⁢</SUP> currents were activated by intracellular Ca<SUP>2⁢</SUP>. 100 nM or 500 nM Ca<SUP>2⁢</SUP> 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 Ca<SUP>2⁢</SUP> in pipette (27.8⁑3.7 pA, n=6). We next examined whether this K<SUP>⁢</SUP> current, recorded with 100 nM Ca<SUP>2⁢</SUP> in pipette, was inhibited by various inhibitors, including Ba<SUP>2⁢</SUP>, TEA and iberiotoxin. The currents were inhibited by 40.4⁑% (n=3), 87.0⁑% (n=5) and 82.5⁑% (n=9) by 1 mM Ba<SUP>2⁢</SUP>, 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 Ca<SUP>2⁢</SUP>. The K<SUP>⁢</SUP> current may play a role in secretory process, since recycling of K<SUP>⁢</SUP> is critical for the initiation and sustaining of Cl<SUP>⁣</SUP> or HCO<SUB>3</SUB><SUP>⁣</SUP> secretion in these cells.