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K Ca 3.1 channels facilitate K + secretion or Na + absorption depending on apical or basolateral P2Y receptor stimulation
Author(s) -
Palmer Melissa L.,
Peitzman Elizabeth R.,
Maniak Peter J.,
Sieck Gary C.,
Prakash Y. S.,
O’Grady Scott M.
Publication year - 2011
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.2011.207548
Subject(s) - apical membrane , stimulation , chemistry , epithelial polarity , receptor , biophysics , p2y receptor , medicine , endocrinology , charybdotoxin , ion transporter , membrane potential , purinergic receptor , biology , biochemistry , membrane
Non‐technical summary The epithelial cells lining the ducts of the human mammary gland are responsible for modifying sodium and potassium concentrations in milk by actively absorbing sodium from and secreting potassium into the ductal fluid. In the present study we show that adenosine triphosphate (ATP) and uridine triphosphate (UTP) can stimulate sodium absorption and potassium secretion by a mechanism that involves increasing intracellular calcium and activation of calcium‐dependent potassium channels. We discovered that addition of ATP or UTP to the luminal surface stimulates potassium secretion, whereas addition of the same concentrations to the epithelial surface normally exposed to the blood produces an increase in sodium absorption. These results provide a better understanding of the signalling mechanisms that control the concentrations of sodium and potassium present in milk.