title: Volume regulation of cultured, transformed, non-pigmented epithelial cells from human ciliary body.
abstract: Electronic cell sizing has been used to measure the volume of cells suspended in isosmotic and in hyposmotic solutions of identical ionic composition. Without inhibitors, the cells displayed a regulatory volume decrease (RVD) following anisosmotic cell swelling with a time constant (tau) of 6.3 +/- 0.9 min (mean +/- S.E.). The RVD was markedly impaired by substituting gluconate for external Cl-, and tau was prolonged by: (i) reducing the chemical gradient favoring K+ loss (by elevating the external [K+] and blocking the Na. K-exchange pump), (ii) blocking the K+ channels with Ba2+, (iii) blocking Cl- channels and Cl-/HCO3 = exchange with DIDS, and (iv) removing external HCO3-. Withdrawing HCO3- may have altered the RVD either directly by inhibiting a Cl-/HCO3- antiport, or indirectly by affecting intracellular pH. The regulatory volume response of ODM Cl-2/SV40 cells is in several respects qualitatively similar to that of non-pigmented epithelial cells of the intact ciliary body. These common characteristics suggest that the cultured cells can serve as a useful model for studying solute and fluid transport across the human ciliary epithelium. The basis for the RVD is likely to be activation of separate K+ and Cl- channels, with or without the parallel operation of coupled K+/H+ and Cl-/HCO3- antiports.
authors: Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085.
authors: R E
authors: RE
authors: Yantorno
authors: M
authors: M
authors: Coca-Prados
authors: T
authors: T
authors: Krupin
authors: M M
authors: MM
authors: Civan
mesh_terms: D002461:Cell Line, Transformed; D002712:Chlorides / Q000378:metabolism; D002924:Ciliary Body / Q000166:cytology* / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D011188:Potassium / Q000378:metabolism
chemical_list: D002712:Chlorides; D007473:Ion Channels; D011188:Potassium