Nitric oxide inhibits whole-cell current in cystic fibrosis pancreatic epithelial cells.

We characterized the effects of nitric oxide (NO) on whole-cell current in pancreatic epithelial cell lines from control (PANC-1) and cystic fibrosis patients (CFPAC-1). The nitric oxide donor S-nitrosoglutathione (GSNO) significantly reduced whole-cell current in CFPAC-1 cells but had no effect in PANC-1 cells. This inhibitory effect of NO could be eliminated by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) or charybdotoxin, suggesting the involvement of DIDS-sensitive Cl- channels and charybdotoxin-sensitive K+ channels. Pretreatment of cells with a selective inhibitor of soluble guanylate cyclase (sGC), 1H-[1,2,4]oxadiazolo[4,3,1]quinoxalin-1-one (ODQ, 10 microM), eliminated the inhibitory effect of NO, but not 8-bromo-cyclic guanosine monophosphate (8-Br-cGMP; 1 mM), indicating that NO acts via a cGMP-dependent pathway. There was a striking difference in cGMP production in response to GSNO in CFPAC-1 cells as compared with PANC-1 cells. GSNO induced a 90-fold increase in cGMP level in CFPAC-1 cells, compared with a threefold increase in PANC-1. Similarly, CFPAC-1 cells showed elevated levels of sGC and constitutive nitric oxide synthase activity as compared with PANC-1 cells. Therefore excessive production of NO, as is seen in inflammatory states, may contribute to the CF phenotype by inhibiting transepithelial ion movement and preventing secretion of digestive enzymes produced by the pancreas.