AJP - Cell Physiology, Vol 260, Issue 6 C1172-C1181, Copyright © 1991 by American Physiological Society
Apical and basolateral membrane conductances in the TBM cell line
J. D. Horisberger
Institut de Pharmacologie, Lausanne, Switzerland.
Cultured cell lines present several advantages over whole organ or ex vivo
isolated epithelium for the physiological and biochemical study of
epithelial transport. We have developed a new technique allowing for
simultaneous intracellular and transepithelial electrophysiological
measurements in the epithelium formed by a cultured cell line grown on thin
collagen membranes. This technique was applied to the TBM 18/23 (toad
bladder origin) cell line. The transepithelial and basolateral membrane
potentials were -30 +/- 11 and -72 +/- 8 (SD) mV (n = 36), respectively.
With the use of the effect of amiloride, which partially blocked the apical
membrane conductance, and circuit analysis, the apical and basolateral
membrane conductances were estimated to 0.7 +/- 0.1 and 2.8 +/- 0.4 mS/cm2,
respectively. A sodium-selective conductive pathway was demonstrated in the
apical membrane, and a barium-sensitive K(+)-selective conductance was
shown to be present in the basolateral membrane. The basolateral membrane
conductance was not modified by sudden inhibition of sodium transport by
amiloride, but it was significantly reduced after a long-term decrease of
Na+ transport. The cultured TBM cell line appears to be a convenient model
to investigate the regulation of membrane ionic conductances in tight
epithelia.
