Effects of hydrostatic pressure on transepithelial transport.

<p>(A) Effects of hydrostatic pressure on transepithelial electrical resistance (TER) in MDCK I cells. The TER was changed to decrease at two days after application of the hydrostatic pressure under the ‘Basal’ condition. (B) The ratio of <i>P</i>_Na to <i>P</i>_Cl (<i>P</i>_Na/<i>P</i>_Cl) under the ‘Apical’ and ‘Basal’ conditions in MDCK I cells. The <i>P</i>_Na/<i>P</i>_Cl was measured at four days after the culture under the ‘Apical’ and ‘Basal’ conditions. The value of <i>P</i>_Na/<i>P</i>_Cl under the ‘Basal’ condition was significantly higher than that under the ‘Apical’ condition. (C) <i>P</i>_Na and <i>P</i>_Cl under the ‘Apical’ and ‘Basal’ conditions in MDCK I cells. The value of <i>P</i>_Na under the ‘Basal’ condition was approximately four-fold higher than that under the ‘Apical’ condition. (D) Immunofluorescence microscopy for claudin-2 and ZO-1 in MDCK I cells at four days after the culture under the ‘Apical’ and ‘Basal’ conditions. Claudin-2 staining was clearly detected at cell-cell contacts in a limited region under the ‘Basal’ condition. Scale bar = 10 μm. (E) Immunoblots for claudin-2 and E-cadherin in MDCK I cells at four days after the culture under the ‘Apical’ and ‘Basal’ conditions. MDCK II cells cultured on filters for six days were used as a positive control. A faint band of claudin-2 was detected under the ‘Basal’ condition in MDCK I cells. (F) Flux of fluorescein and 4 kDa FITC-dextran under the ‘Apical’ and ‘Basal’ conditions in MDCK I cells. The flux was measured at four days after the culture under the ‘Apical’ and ‘Basal’ conditions. The flux of fluorescein under the ‘Basal’ condition was significantly lower than that under the ‘Apical’ condition. * <i>p</i> < 0.05, ** <i>p</i> < 0.01 compared with the ‘Apical’ condition.