The effect of mineral-derived zinc ions on in vitro glucose metabolism of Streptococcus mutans NCTC 10449.
Mouthrinses containing zinc ions inhibit plaque acidogenicity, but the effect is transient. Zinc-containing apatite or zinc phosphate precipitated within dental plaque might serve as a reservoir for zinc ions, thus providing prolonged inhibition of acid formation. Zinc-containing fluorhydroxyapatite was prepared from solutions containing CaCl2, KH2PO4, NaF and increasing amounts of ZnCl2 (0.0, 0.005, 0.02, 0.1, 0.2 or 1 mM; minerals No. 1-6, respectively) by raising the pH with ammonia. Zinc phosphate tetrahydrate (mineral No. 7) was prepared in a similar manner from a solution containing ZnCl2 and KH2PO4 only. Dense cell suspensions of Streptococcus mutans NCTC 10449 were incubated with 14C-glucose and one of the test minerals (No. 1-7). Glycolysis was allowed to proceed, with or without pH control, in a pH-stat. Samples were withdrawn at 1, 2, and 3 min, and extracellular glycolytic metabolites were identified by HPLC. Mineral No. 7 inhibited glycolysis and any pH fall almost completely. With the pH fixed at 5.5, reduction of glucose consumption and lactate formation was 83 and 93%, respectively, compared to the no-zinc control mineral (No. 1). No changes in glucose consumption or lactate formation were evident in the presence of minerals No. 2-6. All apatitic minerals had a buffering effect and, in the absence of pH control, glycolysis was increased due to the higher pH. Detectable levels of fluoride were not released by any mineral into the incubation mixture, and zinc only by minerals No. 6 and 7 in greater than trace amounts.(ABSTRACT TRUNCATED AT 250 WORDS)
Scheie
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Department of Oral Biology, Faculty of Dentistry, University of Oslo, Norway.
Pearce
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D000143:Acids / Q000037:antagonists & inhibitors / Q000378:metabolism; D000641:Ammonia / Q000737:chemistry; D001031:Apatites / Q000138:chemical synthesis / Q000737:chemistry*; D002021:Buffers; D002118:Calcium / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry; D002250:Carbon Radioisotopes; D002712:Chlorides / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003773:Dental Plaque / Q000737:chemistry; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000096:biosynthesis; D010710:Phosphates / Q000138:chemical synthesis / Q000737:chemistry; D013295:Streptococcus mutans / Q000145:classification / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology*; D017967:Zinc Compounds / Q000138:chemical synthesis / Q000737:chemistry
D000143:Acids; D001031:Apatites; D002021:Buffers; D002130:Calcium Phosphates; D002250:Carbon Radioisotopes; D002712:Chlorides; D007773:Lactates; D010710:Phosphates; D017967:Zinc Compounds; C043952:zinc phosphate; D000641:Ammonia; C016837:zinc chloride; D005947:Glucose; D015032:Zinc; C025105:fluorapatite; D002118:Calcium