Expression of sodium-linked nucleoside transport activity in monolayer cultures of IEC-6 intestinal epithelial cells.
Mature, confluent monolayer cultures of IEC-6 rat intestinal epithelial cells in conventional growth media express both Na(+)-linked, concentrative nucleoside transport (NT) activity and equilibrative, inhibitor-sensitive NT activity, but do not show morphologic differentiation. Na(+)-dependent fluxes of Ado and formycin B were minor in early subconfluent IEC-6 monolayers, but increased severalfold to become the major component of influx of these agents in confluent monolayers grown in medium containing Nu-Serum, a commercial medium supplement with a low serum content. In monolayers cultured in medium with fetal bovine serum, cell proliferation rates were similar to those in medium supplemented with Nu-Serum, but expression of Na(+)-linked NT activity was 6-8-fold lower than in monolayers grown in the latter medium. Inclusion of hydrocortisone in growth medium with Nu-Serum caused a 2-fold increase in the expression of Na(+)-linked NT activity. Experiments in which components of medium supplementation were withheld showed that insulin and epidermal growth factor were important in expression of the Na(+)-linked NT activity. Because the Na(+)-linked NT system has a brush border location in fresh intestinal epithelium, it is concluded that the regulated expression of this activity in the IEC-6 monolayers is a differentiative change.
Jakobs
E S
ES
McEachern Laboratory, University of Alberta, Edmonton, Canada.
Van Os-Corby
D J
DJ
Paterson
A R
AR
D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D003470:Culture Media; D004848:Epithelium / Q000378:metabolism; D005573:Formycins / Q000378:metabolism*; D006854:Hydrocortisone / Q000494:pharmacology; D007082:Ileum; D007700:Kinetics; D051381:Rats; D012964:Sodium / Q000494:pharmacology*
D003470:Culture Media; D005573:Formycins; C034561:formycin B; D012964:Sodium; D000241:Adenosine; D006854:Hydrocortisone