Gap junctions mediate glucose transport between GLUT1-positive and -negative cells in the spiral limbus of the rat cochlea.
To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus.
Matsunami
Tatsuya
T
Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Suzuki
Toshihiro
T
Hisa
Yasuo
Y
Takata
Kuniaki
K
Takamatsu
Tetsuro
T
Oyamada
Masahito
M
D000818:Animals; D001692:Biological Transport; D003051:Cochlea / Q000378:metabolism* / Q000648:ultrastructure; D018031:Connexin 43 / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D062793:Occludin; D051381:Rats; D017208:Rats, Wistar; D013137:Spiral Lamina; D019108:Tight Junctions
D018031:Connexin 43; D051272:Glucose Transporter Type 1; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D005947:Glucose