EXPRESSION OF NA,K-ATPASE-ALPHA AND NA,K-ATPASE-BETA ISOFORMS IN THE NEONATAL RAT COCHLEA

The postnatal expression of five Na, K-ATPase alpha (alpha 1, alpha 2, alpha 3) and beta (beta 1, beta 2) subunit isoforms in the rat cochle a was investigated by immunocytochemistry. High levels of expression o f the alpha 1 and beta 2 isoforms were observed in stria vascularis (S V) at all developmental stages. alpha 1 and beta 1 isoforms showed a d istinct time-dependent developmental expression pattern in tissues of the spiral ligament (SL) and spiral limbus (SLi). Limited, temporary e xpressions of alpha 2 and alpha 3 subunit isoforms were found in SV an d SL. Expression of each isoform was also;seen in organ of Corti (OC), spiral ganglion (SG), cochlear nerve (CN) and Kolliker's Organ (KO). These observations suggest that individual isoforms may exert specific actions postnatally during final cochlear maturation.