Electrogenic sodium absorption and chloride secretion by an inner medullary collecting duct cell line (mIMCD-K2).
The initial segment of the inner medullary collecting duct (IMCDi) absorbs Na+ by an electrogenic mechanism and plays an important role in regulating the composition and volume of the urine. The purpose of the present study was to establish a permanent cell line derived from the IMCDi, which has the ion transport properties of the IMCDi in vivo. To this end, we isolated IMCD cells from the IMCDi of a mouse, Tg(SV40E) Bri 7, transgenic for the early region of SV40 (large T antigen) and established a permanent cell line, mIMCD-K2, by clonal dilution. mIMCD-K2 cells retain many differentiated characteristics of the IMCDi, including amiloride-sensitive electrogenic Na+ absorption stimulated by nanomolar concentrations of aldosterone. Aldosterone (1.5 x 10(-6) M) increased Na+ absorption from 0.2 +/- 0.1 to 4.6 +/- 1.7 microA/cm2. In addition, the cells secrete Cl- by an electrogenic mechanism at a rate of 0.5 +/- 0.1 microA/cm2. We propose that IMCDi cells either absorb or secrete NaCl depending on NaCl homeostasis. The mIMCD-K2 cell line should be useful for studying the cellular mechanisms responsible for electrogenic Na+ and Cl- transport in the IMCDi.
Kizer
N L
NL
Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03755.
Lewis
B
B
Stanton
B A
BA
D000042:Absorption / Q000187:drug effects; D000450:Aldosterone / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division; D002460:Cell Line; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004594:Electrophysiology; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D012964:Sodium / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D002712:Chlorides; D062367:ortho-Aminobenzoates; D000450:Aldosterone; D000584:Amiloride; C001209:fenamic acid; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase