P-glycoprotein expression and the regulation of [Ca2+]i during cell swelling Academic Article uri icon

Overview

MeSH Major

  • Eccrine Glands
  • Epithelial Cells
  • Hyperhidrosis
  • Sweat

abstract

  • Hypotonic solutions increase [Ca2+]i in P-gp-expressing adenocarcinoma cells selected for adrimaycin resistance (A2780.ad), but not in this strain's parental line (A2780.wt) (Bovell and Wilson, J. Physiol. 489: 135P-136P, 1996). To explore the possibility that this reflects differential expression of P-gp, we established a revertant strain (A2780.rev) that contained fewer cells in which P-gp could be detected by cytochemistry (A2780.wt: 0%, A2780.ad: 93 ± 5%. A2780.rev: 34 ± 7%). This strain was also more sensitive to adriamycin (IC50 values: A2780.wt: 0.001 ± 0.0003 μM, A2780.ad: 5.6 ± 0.7 μM, A2780.rev: 0.6 ± 0.4 μM) and exported rhodamine-123, a fluorescent P-gp substrate, at a reduced rate (half times: A2780.wt: > 5 h, A2780.ad: 5.5 ± 0.8 min, A2780.rev, 116 ± 27 min). Cell swelling increased [Ca2+]i in A2780.ad cells (rise in Fura-2 ratio: 0.36 ± 0.09) but evoked a smaller response in the A2780.rev cells (0.12 ± 0.03) whilst the A2780.wt cells were unresponsive. However, 0.1 μM ionomycin evoked similar responses in each stain (A2780.wt: 1.5 ± 0.24, A2780.ad: 1.0 ± 0.11, A2780.rev: 1.2 ± 0.15).

publication date

  • March 20, 1998

Research

keywords

  • Academic Article

Additional Document Info

start page

  • A1022

volume

  • 12

number

  • 5