title: Polarity of volume-regulatory increase by Necturus gallbladder epithelium.
abstract: Necturus gallbladder epithelial cells respond to the presence of a hypertonic perfusate in either bathing solution by first shrinking due to osmotic water loss and then swelling back to their original volume (volume-regulatory increase). Previous investigations involving increases in the osmolality of the mucosal bath had suggested that volume-regulatory increase was due to the activation of ion exchangers in the apical cell membrane. In the present study the sidedness of the transport processes involved in volume-regulatory increase was investigated. The osmolality of the serosal bath was increased by 18% either in the absence of HCO3- or when an inhibitor of volume-regulatory increase, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), was added to the mucosal or serosal bath. Volume regulation was HCO3- dependent. DIDS was only effective in inhibiting volume regulation when it was added to mucosal bathing solution, suggesting that volume-regulatory increase depended on transport across the apical membrane. Volume-regulatory increase could also be activated by first swelling the cells in hypotonic solution and then returning the tissue to control Ringer solution. The volume-regulatory increase that occurred upon return to control Ringer was also shown to be sensitive to DIDS in the mucosal bath.
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D004848:Epithelium / Q000378:metabolism; D005704:Gallbladder / Q000378:metabolism*; D006982:Hypertonic Solutions; D007552:Isotonic Solutions / Q000494:pharmacology; D009092:Mucous Membrane / Q000378:metabolism; D009337:Necturus / Q000378:metabolism*; D009338:Necturus maculosus / Q000378:metabolism*; D010710:Phosphates / Q000494:pharmacology; D000077331:Ringer's Solution; D012704:Serous Membrane / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D006982:Hypertonic Solutions; D007552:Isotonic Solutions; D010710:Phosphates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000077331:Ringer's Solution; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid