Distribution of the Na,K-ATPase alpha subunit in the rat spiral ganglion and organ of corti.
Processing of sound in the cochlea involves both afferent and efferent innervation. The Na,K-ATPase (NKA) is essential for cells that maintain hyperpolarized membrane potentials and sodium and potassium concentration gradients. Heterogeneity of NKA subunit expression is one mechanism that tailors physiology to particular cellular demands. Therefore, to provide insight into molecular differences that distinguish the various innervation pathways in the cochlea, we performed a variety of double labeling experiments with antibodies against three of the alpha isoforms of the NKA (NKA alpha 1-3) and markers identifying particular subsets of neurons or supporting cells in whole mount preparations of the organ of Corti and spiral ganglion. We found that the NKA alpha 3 is abundantly expressed within the membranes of the spiral ganglion somata, the type I afferent terminals contacting the inner hair cells, and the medial efferent terminals contacting the outer hair cells. We also found expression of the NKA alpha 1 in the supporting cells that neighbor the inner hair cells and express the glutamate transporter GLAST. These findings suggest that both the NKA alpha 1 and NKA alpha 3 are poised to play an essential role in the regulation of the type I afferent synapses, the medial efferent synapses, and also glutamate transport from the afferent-inner hair cell synapse.
McLean
Will J
WJ
Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA.
Smith
K Anne
KA
Glowatzki
Elisabeth
E
Pyott
Sonja J
SJ
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D027341:Excitatory Amino Acid Transporter 1 / Q000096:biosynthesis; D018698:Glutamic Acid / Q000378:metabolism; D006199:Hair Cells, Auditory, Inner / Q000201:enzymology; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000096:biosynthesis; D007760:Labyrinth Supporting Cells / Q000201:enzymology; D009475:Neurons, Afferent / Q000201:enzymology; D009476:Neurons, Efferent / Q000201:enzymology; D009925:Organ of Corti / Q000166:cytology / Q000201:enzymology*; D017729:Presynaptic Terminals / Q000201:enzymology; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis*; D013136:Spiral Ganglion / Q000166:cytology / Q000201:enzymology*; D013569:Synapses / Q000502:physiology
D027341:Excitatory Amino Acid Transporter 1; D007527:Isoenzymes; C493392:Slc1a3 protein, rat; D018698:Glutamic Acid; C499075:Atp1a1 protein, rat; C498532:Atp1a2 protein, rat; C541459:Atp1a3 protein, rat; D000254:Sodium-Potassium-Exchanging ATPase