Retention of basic electrophysiologic properties by human sweat duct cells in primary culture

The present investigation was undertaken to examine the usefulness of cultured human sweat duct cells for ion transport and related studies in the genetic disease, cystic fibrosis. Electrical properties of cultured duct (CD) cells were compared with electrical properties of microperfused duct (MPD) cells. The resting apical membrane potential (Va) of the CD cells was -26.4 +/- 0.9 mV, n = 158 cells as compared to -24.3 +/- 0.6 mV, n = 105 of MPD cells. The Na+-K+ pump inhibitor ouabain, when applied to the apical surface of the CD cells and basolateral surface of MPD cells, depolarized both CD cells (from -28.6 +/- 3.6 to -16.8 +/- 2.4 mV, n = 5) and MPD cells (from -23.8 +/- 0.5 mV to -19.5 +/- 1.8 mV, n = 6). The Na+ conductance inhibitor amiloride applied to the apical surface hyperpolarized the apical membrane potentials (Va) of CD cells and MPD cells by -13.2 +/- 1.4 mV, n = 43 and -34.3 +/- 3.1 mV, n = 19), respectively, indicating the presence of amiloride sensitive Na+ channels in both groups of cells. However, the amiloride sensitivity of CD cells was dependent on the age of the culture. Cl- substitution at the apical side by the impermeant anion gluconate depolarized the Va of CD cells and MPD cells by 12.2 +/- 0.9 mV, n = 32 and 37.9 +/- 4.3 mV, n = 12, respectively. The effect of beta-adrenergic agonist isoproterenol (IPR), was inconsistent. In CD cells, IPR either hyperpolarized (delta Va = -8.3 +/- 1.2 mV, n = 5) or depolarized (delta Va = 8.2 +/- 2.3 mV, n = 4) or had no effect, n = 2. In contrast, most of the MPD cells did not respond to IPR, but three cells had a varied response to IPR. Our results suggest that CD cells, like MPD cells, retain significant Na+ and Cl- conductances. CD cells seem to have developed a higher sensitivity to beta-adrenergic stimulation in tissue culture as compared to MPD cells.