title: Intracellular Cl- concentration in striated intralobular ducts from rabbit mandibular salivary glands.
abstract: Intralobular striated ducts have been isolated from rabbit mandibular salivary glands and maintained in primary culture for up to 2 days. Such ducts were loaded with the Cl(-)-sensitive fluorescent dye N-(ethoxycarbonylmethyl)-(6-methoxyquinolinium bromide) (MQAE) and intracellular Cl- concentration ([Cl-]i) monitored using a fluorescence microscope. Intracellular Cl- could be rapidly and reversibly emptied from striated duct cells by replacing Cl- in the superfusing solution with NO(3)-. [Cl-]i could be lowered by removal of external Na+, exposure to 10 microM amiloride or to 10 microM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS). Both amiloride and DIDS were able to inhibit the recovery of [Cl-]i after an initial exposure to Na(+)- or Cl(-)-free solution. The amiloride derivatives, benzamil (2 microM) and N-isobutyl-N-methylamiloride (MIBA), (10 microM) also lowered [Cl-]i by similar amounts as 10 microM amiloride. Varying external K+ concentration ([K+]o) also affected [Cl-]i. Increasing [K+]o increased [Cl-]i, but decreasing [K+]o did not decrease [Cl-]i. Instead, [Cl-]i was also increased when [K+]o was lowered below the control value. Bumetanide (0.1 mM) lowered [Cl-]i by only a small amount, while ouabain (1 mM) had no significant effect on [Cl-]i. These data are consistent with current models of electrolyte transport in salivary ducts which include Cl- channels, Na+ channels, and Na+/H+ exchangers in the apical membrane. The effects of low [K+]o can be interpreted in terms of a K(+)-dependent exit mechanism for Cl-.
authors.affiliation: Department of Physiological Sciences, University of Manchester, UK.
authors.forename: K R
authors.initials: KR
authors.lastname: Lau
authors.forename: R L
authors.initials: RL
authors.lastname: Evans
authors.forename: R M
authors.initials: RM
authors.lastname: Case
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005453:Fluorescence; D006531:HEPES / Q000494:pharmacology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D008297:Male; D008334:Mandible; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D011804:Quinolines / Q000378:metabolism; D011817:Rabbits; D012469:Salivary Glands / Q000378:metabolism*
chemical_list: D002712:Chlorides; D011804:Quinolines; C078229:N-(6-methoxyquinolyl)acetoethyl ester; D000584:Amiloride; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D006531:HEPES