Extracellular cation sensing by the enterocyte: prediction of a novel divalent cation "receptor".
We report that the divalent cation Ni2+ elicits elevations in the cytosolic free Ca2+ concentration ([Ca2+]) in cultured enterocytes. These elevations were monophasic, each response consisting of a rapid initial transient rise of cytosolic [Ca2+] to a peak value followed by an exponential decline. The magnitude of the cytosolic [Ca2+] elevation varied with the concentration of applied Ni2+. In some cells, a single application of Ni2+ induced oscillatory changes in cytosolic [Ca2+]. There was also evidence for use-dependent inactivation: a conditioning application of Ni2+ substantially attenuated the response resulting from its subsequent application. Our findings thus demonstrate the existence of a divalent cation-sensing "receptor" on the enterocyte. This putative receptor may play a role in regulating mineral absorption across the enterocyte membrane.
Pazianas
M
M
Bone Research Unit, St. George's Hospital Medical School, London, UK.
Adebanjo
O A
OA
Shankar
V S
VS
James
S Y
SY
Colston
K W
KW
Maxwell
J D
JD
Zaidi
M
M
D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism*; D002460:Cell Line; D003106:Colon / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009532:Nickel / Q000494:pharmacology*; D009991:Oscillometry; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013997:Time Factors
D002413:Cations, Divalent; D011956:Receptors, Cell Surface; D009532:Nickel; D002118:Calcium