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

We investigatedthe relationship between pI_Cln,the volume-activated Clcurrent, and volume regulation in native bovine nonpigmented ciliaryepithelial (NPCE) cells. Immunofluorescence studies demonstrated thepresence of pI_Cln protein in theNPCE cells. Exposure to hypotonic solution activated aCl current and inducedregulatory volume decrease (RVD) in freshly isolated bovine NPCE cells.Three antisense oligonucleotides complementary to humanpI_Cln mRNA were used in theexperiments. The antisense oligonucleotides were taken up by the cellsin a dose-dependent manner. The antisense oligonucleotides, designed tobe complementary to the initiation codon region of the humanpI_Cln mRNA, "knocked down"the pI_Cln proteinimmunofluorescence, delayed the activation of volume-activatedCl current, diminished thevalue of the current, and reduced the ability of the cells to volumeregulate. We conclude that pI_Cln is involved in the activation pathway of the volume-activated Cl current and RVDfollowing hypotonic swelling.