title: Properties of the luminal membrane of isolated perfused rat pancreatic ducts. Effect of cyclic AMP and blockers of chloride transport.
abstract: The aim of the present study was to investigate by what transport mechanism does HCO-3 cross the luminal membrane of pancreatic duct cells, and how do the cells respond to stimulation with dibutyryl cyclic AMP (db-cAMP). For this purpose a newly developed preparation of isolated and perfused intra- and interlobular ducts of rat pancreas was used. Responses of the epithelium to inhibitors and agonists were monitored by electrophysiological techniques. Addition of HCO-3/CO2 to the bath side of nonstimulated ducts depolarized the PD across the basolateral membrane (PDbl) by about 9 mV, as also observed in a previous study [21]. This HCO-3 effect was abolished by Cl- channel blockers or SITS infused into the lumen of the duct: i.e. 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB, 10(-5) M) hyperpolarized PDbl by 8.2 +/- 1.6 mV (n = 13); 3',5-dichlorodiphenylamine-2-carboxylic acid (DCl-DPC, 10(-5) M) hyperpolarized PDbl by 10.3 +/- 1.7 mV (n = 10); and SITS hyperpolarized PDbl by 7.8 +/- 0.9 mV (n = 4). Stimulation of the ducts with db-cAMP in the presence of bath HCO-3/CO2 resulted in depolarization of PDbl, the ductal lumen became more negative and the fractional resistance of the luminal membrane decreased. Together with forskolin (10(-6) M), db-cAMP (10(-4) M) caused a fast depolarization of PDbl by 33.8 +/- 2.5 mV (n = 6). When db-cAMP (5 x 10(-4) M) was given alone in the presence of bath HCO-3/CO2, PDbl depolarized by 25.3 +/- 4.2 mV (n = 10).(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Physiologisches Institut, Albert-Ludwigs-Universität, Freiburg, Federal Republic of Germany.
authors: I
authors: I
authors: Novak
authors: R
authors: R
authors: Greger
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin; D005260:Female; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D010183:Pancreatic Ducts / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D007473:Ion Channels; D005576:Colforsin; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D003994:Bucladesine