Association of intrinsic pICln with volume-activated Cl- current and volume regulation in a native epithelial cell

We investigated the relationship between pI(Cln), the volume-activated Cl- current, and volume regulation in native bovine nonpigmented ciliary epithelial (NPCE) cells. Immunofluorescence studies demonstrated the presence of pI(Cln) protein in the NPCE cells. Exposure to hypotonic solution activated a Cl- current and induced regulatory volume decrease (RVD) in freshly isolated bovine NPCE cells. Three antisense oligonucleotides complementary to human pI(Cln) mRNA were used in the experiments. The antisense oligonucleotides were taken up by the cells in a dose-dependent manner. The antisense oligonucleotides, designed to be complementary to the initiation codon region of the human pI(Cln) mRNA, "knocked down" the pI(Cln) protein immuno fluorescence, delayed the activation of volume-activated Cl- current, diminished the value of the current, and reduced the ability of the cells to volume regulate. We conclude that pI(Cln) is involved in the activation pathway of the volume-activated Cl- current and RVD following hypotonic swelling.