Expression of a sodium bicarbonate cotransporter in human parotid salivary glands

K. Park, P. T. Hurley, E. Roussa, G. J. Cooper, C. P. Smith, F. Thévenod, M. C. Steward, R. M. Case

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    The human parotid gland secretes much of the bicarbonate that enters the mouth. Prompted by studies of animal models, this study sought evidence for the expression of a functional Na+-HCO3- cotransporter (NBC) in human parotid acinar cells. Microfluorometric measurements of intracellular pH in isolated acini showed that the recovery from an acid load was achieved in part by HCO3- uptake via a Na+-dependent, DIDS-sensitive mechanism. By reverse transcriptase-polymerase chain reaction, a full-length NBC1 clone was obtained showing more than 99% homology with the human pancreatic isoform hpNBC 1. Expressed in Xenopus oocytes, the electrogenicity of the transporter was detected as an inwardly directed, Na+- and HCO3--dependent flux of negative charge. Immunohistochemistry using antibodies raised to NBC1 showed strong staining of the basolateral membrane of the acinar cells. Therefore, it was concluded that a functional electrogenic Na+-HCO3- cotransporter is expressed in the human parotid gland, and that it contributes to pH regulation in the acinar cells and could play a significant part in salivary secretion. © 2002 Elsevier Science Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)1-9
    Number of pages8
    JournalArchives of oral biology
    Issue number1
    Publication statusPublished - 2002


    • Bicarbonate secretion
    • Intracellular pH
    • NBC


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