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Delayed expression of large conductance K + channels reshaping agonist‐induced currents in mouse pancreatic acinar cells
Author(s) -
Oshiro Takako,
Takahashi Hidenori,
Ohsaga Atsushi,
Ebihara Satoru,
Sasaki Hidetada,
Maruyama Yoshio
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.077834
Subject(s) - secretagogue , endocrinology , medicine , patch clamp , secretion , chemistry , membrane potential , potassium channel , intracellular , biology , microbiology and biotechnology , electrophysiology , biophysics
Epithelial secretory cells display cell‐specific mechanisms of fluid secretion and express large conductance voltage‐ and Ca 2+ ‐activated K + (Maxi‐K) channels that generate the membrane negativity for effective Cl − exit to the lumen. Rat and mouse pancreatic acinar cells had been thought to be peculiar in this sense because of the previously reported lack of Maxi‐K channels. However, this view is not entirely correct as evidenced in the present paper. Searching for their presence in pancreatic acinar cells in mice from 5 to 84 weeks of age with patch‐clamp current measurements, we demonstrated that the expression of Maxi‐K channels is regulated in an age‐associated manner after birth. The expression started at approximately 12 postnatal weeks and increased steadily up to 84 weeks. In support of this, RT‐PCR could not detect mSlo mRNA, the Maxi‐K gene, at either 7 or 8 weeks but could at 58 and 64 postnatal weeks. These results suggest that a key steering element for fluid secretion, the Maxi‐K channel, is progressively re‐organized in rodent pancreas. A pancreatic secretagogue, acetylcholine, evoked Maxi‐K channel current overlapping to various degrees on the previously known current response. This suggests that the rise in internal Ca 2+ activates Maxi‐K channels which reshape the mode of secretagogue‐evoked current response and contribute to Cl − driving in fluid secretion in an age‐associated fashion.