NORMALIZATION OF ION-TRANSPORT IN MURINE CYSTIC-FIBROSIS NASAL EPITHELIUM USING GENE-TRANSFER

The murine nasal epithelium was investigated by the short-circuit curr ent (SCC) technique. Electrogenic sodium absorption was revealed by ad dition of amiloride and calcium-dependent chloride secretion by the ad dition of 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBHQ)/ionomycin. In the presence of these agents a further increase in SCC was obtained by addition of forskolin. Epithelia from both cystic fibrosis (CF) nu ll (Cftr(tm1Cam)) and CF Delta F508 (Cftr(tm2Cam)) mice had enhanced s odium absorption compared with controls, whereas only Delta F508 epith elia had increased calcium-dependent chloride secretion. Both strains gave nasal epithelia that showed significantly reduced responses to fo rskolin, due to the absence of CF transmembrane conductance regulator (CFTR) chloride channels. In Cftr(tm2Cam) nasal epithelia the forskoli n responses were not significantly different from zero. Transfection o f these mice with the plasmid pTRIAL10-CFTR2 complexed with cationic l iposomes normalized the transporting activity in the nasal epithelium. Basal SCC and calcium-dependent chloride secretion were significantly reduced, whereas CFTR-dependent chloride secretion was increased to n ormal values. Amiloride-sensitive SCC was reduced-by transfection but failed to reach significance. The similarity of murine CF nasal epithe lium to that in human CF airways makes the model valuable for gene the rapy studies.