A role of salivary carbonic anhydrase VI in dental plaque.
OBJECTIVE
Carbonic anhydrase (CA) VI is a unique secreted isozyme of CA, which catalyzes the reversible reaction CO2 +H2O<-->H+ +HCO3-. CA VI has been thought to provide a greater buffering capacity to fluids into which it is secreted. This study was performed to confirm this in saliva.


METHODS
Nine healthy subjects participated in the study. The pH of the dental plaque from each subject was monitored after a mouth rinse with 10% sucrose with or without 10(-5)M acetazolamide, a specific inhibitor of CA. Also CA was examined in plaque by enzyme histochemistry, immunohistochemistry and Western blot analysis.


RESULTS
Though sucrose and sucrose plus inhibitor yielded Stephan curves with a similar temporal pattern, the pH values of the latter were significantly lower than those of the former. Plaque exhibited CA activity by enzyme histochemistry. Immunohistochemistry and Western analysis demonstrated that the activity was due to CA VI but not to CA I or CA II.


CONCLUSIONS
The results indicate that CA VI in saliva penetrates plaque and facilitates acid neutralization by salivary bicarbonate. Therefore, CA VI may be considered an anti-caries protein in saliva.
Kimoto
Masaya
M
Department of Oral Pathology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
Kishino
Mitsunobu
M
Yura
Yoshiaki
Y
Ogawa
Yuzo
Y
D000086:Acetazolamide / Q000494:pharmacology; D000328:Adult; D015153:Blotting, Western; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D002256:Carbonic Anhydrases / Q000502:physiology*; D003773:Dental Plaque / Q000201:enzymology* / Q000378:metabolism; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007124:Immunoenzyme Techniques; D008297:Male; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000502:physiology*; D012463:Saliva / Q000201:enzymology*; D013395:Sucrose
D002257:Carbonic Anhydrase Inhibitors; D021122:Protein Subunits; D013395:Sucrose; D002256:Carbonic Anhydrases; C477051:carbonic anhydrase VI; D000086:Acetazolamide