Carbohydrates in the cell surface of hair cells from the guinea pig cochlea.

The presence of cell surface carbohydrates was investigated in intact, non-fixed outer hair cells (OHCs) of guinea pigs using fluorescein isothiocyanate (FITC) and rhodamine (TRITC) lectins. By means of wheat germ agglutinin (WGA) N-acetyl-D-glucosamine was shown in the entire OHC membrane, including the stereocilia. Binding of WGA in OHCs to neuraminic acid was excluded by preincubation with neuraminidase. Moreover, FITC-Limulus polyphemus, a specific lectin for neuraminic acid, showed no fluorescence on OHCs. Neutral saccharides, like alpha-D-mannose and/or alpha-D-glucose, were mainly observed at the cuticular plate and at the basal cell pole with FITC-concanavalin A. A weaker fluorescence was seen at the lateral cell wall. Two branched oligosaccharides, composed of beta-galactose, N-acetyl-D-glucosamine and mannose, were demonstrated by TRITC-Phaseolus vulgaris (PHA-E/L) in the entire OHC membrane. A spot-like binding of soybean agglutinin to N-acetyl-D-galactosamine could be demonstrated in the region of the cuticular plate. However, using Helix pomatia, the subtype N-acetyl-alpha-D-galactosamine was not detectable. Moreover, there was no binding of Ulex europaeus or of Arachis hypogea (PNA) to OHCs, suggesting the absence of considerable amounts of L-fucose and of galactose-beta-3-N-acetylgalactosamine. The results indicate that N-acetyl-D-glucosamine, alpha-D-mannose and alpha-D-glucose can be considered the major components of the OHC glycocalix. We suggest that they have a function as an anchoring structure in interstereociliary links as well as in hair bundle connections to the tectorial membrane.(ABSTRACT TRUNCATED AT 250 WORDS)