title: Odontoblast transport of sulphate--the in vitro influence of fluoride.
abstract: The present study reports the development of a culture system for the analysis of 35S-sulphate release from odontoblasts in vitro. Pulpless longitudinally split rat incisors were cultured in supplemented minimum essential medium (alphaMEM) with 20 microCi 35S-sulphate per ml, 20 microCi 3H-mannitol per ml for 1h. Teeth were then transferred to fresh unlabelled media and aliquots of media were removed and the level of 35S-sulphate 3H-mannitol determined. Results indicated a two phase release of 35S-sulphate into the media, and comparison with pulp tissue indicated a specific release pattern. Transport of sulphate is essential for correct synthesis and glycosylation of macromolecules such as proteoglycans (PG). Previous studies have shown that post-translational modifications of these proteins can be influenced by excess fluoride, resulting in decreased sulphation and elongation of glycosaminoglycan (GAG) chains. Therefore the influence of fluoride on sulphate transport, using the optimised culture system was also investigated. Inclusion of 6mM fluoride during pulse labelling caused a significant decrease of 35S-sulphate (P<0.0001) during the initial release phase. Inclusion of 3 and 6mM fluoride only in the post-labelling incubation media resulted in a significant decrease in the release of 35S-sulphate (P<0.0001), during the total time course. The influence of fluoride was not dose dependent. Inclusion of a specific chloride channel blocker SITS, into the culture system indicated that 35S-sulphate transport may in part be via this route. Fluoride would therefore appear to influence the transport of 35S-sulphate across the odontoblast membrane, potentially via a chloride channel.
authors.affiliation: Department of Clinical Dental Sciences, The University of Liverpool, Edwards Building, Daulby Street, Liverpool L69 3GN, UK. ammilan@liv.ac.uk
authors.forename: A M
authors.initials: AM
authors.lastname: Milan
authors.forename: R J
authors.initials: RJ
authors.lastname: Waddington
authors.forename: P M
authors.initials: PM
authors.lastname: Smith
authors.forename: G
authors.initials: G
authors.lastname: Embery
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D018929:Cell Culture Techniques / Q000379:methods; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D005459:Fluorides / Q000494:pharmacology*; D008297:Male; D009804:Odontoblasts / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013431:Sulfates / Q000493:pharmacokinetics*; D013462:Sulfur Radioisotopes / Q000378:metabolism
chemical_list: D018118:Chloride Channels; D013431:Sulfates; D013462:Sulfur Radioisotopes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D005459:Fluorides