Salivary carbonic anhydrase VI and its relation to salivary flow rate and buffer capacity in pregnant and non-pregnant women Jyrki Kivela ¨ a,b, *, Merja Laine c , Seppo Parkkila a,d , Hannu Rajaniemi a a Department of Anatomy and Cell Biology, University of Oulu, FIN-90014 Oulu, Finland b Institute of Dentistry, University of Helsinki, Helsinki, Finland c Departments of Cariology and Periodontology, Institute of Dentistry, University of Turku, Lemminka ¨isenkatu 2, FIN-20520 Turku, Finland d Institute of Medical Technology, Tampere University Hospital, University of Tampere, Lenkkeilija¨nkatu 6, FIN-33520 Tampere, Finland Accepted 13 March 2003 Introduction Saliva does much to maintain oral health, one important function being to counteract pH changes in the oral cavity. The CO 2 —carbonic acid—bicarbo- nate system, phosphate system and proteins form the main buffer systems in saliva, although proteins contribute to buffering only at low salivary pH (5.0), when the other two systems are less effec- tive. 1 The CO 2 —carbonic acid—bicarbonate system is responsible for most of the buffering capacity in whole saliva, the bicarbonate concentration increasing with stimulation of flow rate, e.g. during eating. 2 The salivary glands are able to produce bicarbonate from CO 2 , yielding salivary bicarbonate Archives of Oral Biology (2003) 48, 547—551 KEYWORDS Buffering capacity; Carbonic anhydrase; Hormonal regulation; Human; Postpartum; Pregnancy; Saliva; Secretion Summary Objective: Previous studies have shown that pregnancy may have unfavour- able effects on oral health. The pH and buffer capacity (BC) of paraffin-stimulated saliva, for example, have been found to decrease towards late pregnancy. Salivary carbonic anhydrase VI (CA VI) probably protects the teeth by accelerating the neu- tralization of hydrogen ions in the enamel pellicle on dental surfaces. Since estrogens and androgens are known to regulate CA expression in some tissues, we studied here whether salivary CA VI concentration shows pregnancy-related changes. Design: Paraffin-stimulated salivary samples were collected from nine pregnant women 1 month before delivery and about 2 months afterwards and assayed for salivary CA VI concentration, BC and flow rate. The enzyme concentration was determined using a specific time-resolved immunofluorometric assay. The control group consisted of 17 healthy non-pregnant women. Results: The results indicated that salivary CA VI levels varied markedly among individuals, but no significant differences in mean concentra- tions were seen between the samples collected during late pregnancy and postpartum. BC values were lower during pregnancy, however. Conclusions: Our findings suggest that CA VI secretion is not significantly affected by the hormonal alterations associated with pregnancy, and confirm the earlier reports that CA VI is not involved in the regulation of actual salivary BC. ß 2003 Elsevier Science Ltd. All rights reserved.  Corresponding author. Present address: Central Military Hospital, P.O. Box 50, FIN-00301 Helsinki, Finland. Tel.: þ358-50-3247761; fax: þ358-9-18125827. E-mail address: jyrki.kivela@fimnet.fi (J. Kivela¨). 0003–9969/03/$ — see front matter ß 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0003-9969(03)00096-7