title: Ca2+-activated Cl- channel currents in mammary secretory cells from lactating mouse.
abstract: The Cl-secretion via Ca2+-activated Cl-channel (CaCC) is critical for fluid secretion in exocrine glands like the salivary gland. Also in the mammary gland, it has been hypothesized that CaCC plays an important role in the secretion of Cl-and aqueous phase of milk. However, there has been no evidence for the functional expression of CaCC in native mammary secretory (MS) cells of lactating animals. We therefore assessed membrane current in MS cells that were freshly isolated from lactating mice using whole cell patch-clamp techniques. In MS cells, we detected CaCC current that exhibited the following characteristics: 1) Ca2+-dependent activation at the concentrations of submicromolar range; 2) voltage-dependent activation; 3) slow kinetics for activation and deactivation; 4) outward rectification of the steady-state current; 5) anion permeability in the sequence of I-> NO3-> Br-> Cl->> glutamate; 6) inhibition by Cl-channel blockers (niflumic acid, DIDS, and CaCCinh-A01). These characteristics of native CaCC current were similar to reported characteristics of heterologously expressed TMEM16A. RT-PCR analyses showed the expression of multiple CaCC channels including TMEM16A, Best1, and Best3 in the mammary glands of lactating mice. Immunohistochemical staining revealed the localization of TMEM16A protein at the apical membrane of the MS cells. Collectively, our data strongly suggest that MS cells functionally express CaCC, which is at least partly constituted by TMEM16A. The CaCC such as TMEM16A at the apical membrane of the MS cells may influence the quantity and/or quality of milk.
authors: Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and akami@obihiro.ac.jp.
authors: Akihiro
authors: A
authors: Kamikawa
authors: Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors: Osamu
authors: O
authors: Ichii
authors: Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and.
authors: Junpei
authors: J
authors: Sakazaki
authors: Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and.
authors: Toru
authors: T
authors: Ishikawa
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D000075369:Anoctamin-1; D000075002:Bestrophins; D002118:Calcium / Q000378:metabolism*; D018118:Chloride Channels / Q000378:metabolism*; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D007774:Lactation / Q000378:metabolism*; D008297:Male; D042361:Mammary Glands, Human / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010539:Permeability
chemical_list: C531181:ANO1 protein, mouse; D000838:Anions; D000075369:Anoctamin-1; C491856:Best1 protein, mouse; D000075002:Bestrophins; D018118:Chloride Channels; D005136:Eye Proteins; D007473:Ion Channels; C491853:Vmd2L3 protein, mouse; D002118:Calcium
keywords: CaCC; lactation; mammary gland; mammary secretory cell; patch-clamp