Sodium-Calcium Exchangers in Rat Ameloblasts

Reijiro Okumura; Yoshiyuki Shibukawa; Takashi Muramatsu; Sadamitsu Hashimoto; Kan-Ichi Nakagawa; Masakazu Tazaki; Masaki Shimono

Journal of Pharmacological Sciences (Jan 2010)

Sodium-Calcium Exchangers in Rat Ameloblasts

Reijiro Okumura,
Yoshiyuki Shibukawa,
Takashi Muramatsu,
Sadamitsu Hashimoto,
Kan-Ichi Nakagawa,
Masakazu Tazaki,
Masaki Shimono

Affiliations

Reijiro Okumura: Oral Health Science Center, hrc7, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Endodontics, Pulp and Periapical Biology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Pathology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
Yoshiyuki Shibukawa: Oral Health Science Center, hrc7, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Physiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Corresponding author. [email protected]
Takashi Muramatsu: Oral Health Science Center, hrc7, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Pathology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
Sadamitsu Hashimoto: Oral Health Science Center, hrc7, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Pathology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
Kan-Ichi Nakagawa: Department of Endodontics, Pulp and Periapical Biology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
Masakazu Tazaki: Oral Health Science Center, hrc7, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan; Department of Physiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan
Masaki Shimono: Department of Pathology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan

Journal volume & issue: Vol. 112, no. 2
pp. 223 – 230

Abstract

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Although the central role of ameloblasts in synthesis and resorption of enamel matrix proteins during amelogenesis is well documented, the Ca2+-transport/extrusion mechanism remains to be fully elucidated. To clarify Ca2+-transport in rat ameloblasts, we investigated expression and localization of Na+-Ca2+ exchanger (NCX) isoforms and the functional characteristics of their ion transporting/pharmacological properties. RT-PCR and immunohistochemical analyses revealed expression of NCX1 and NCX3 in ameloblasts, localized in the apical membrane. In patch-clamp recordings, Ca2+ efflux by Na+-Ca2+ exchange showed dependence on external Na+. Ca2+ influx by Na+-Ca2+ exchange, measured by fura-2 fluorescence, showed dependence on extracellular Ca2+ concentration, and it was blocked by NCX inhibitors KB-R7943, SEA0400, and SN-6. These results showed significant expression of NCX1 and NCX3 in ameloblasts, indicating their involvement in the directional Ca2+ extrusion pathway from cells to the enamel mineralizing front. Keywords:: transporter, enamel, mineralization, channel, SLC8 gene family

Published in Journal of Pharmacological Sciences

ISSN: 1347-8613 (Print)
Publisher: Elsevier
Country of publisher: Japan
LCC subjects: Medicine: Therapeutics. Pharmacology
Website: http://www.journals.elsevier.com/journal-of-pharmacological-sciences

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