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Creatine kinase in epithelium of the inner ear
1Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston 29425.
Abstract:
Epithelium of the inner ear in the gerbil and mouse was examined immunocytochemically for presence of creatine kinase (CK). Marginal cells of the cochlear stria vascularis and dark cells and transitional cells of the vestibular system were found to contain an abundance of the MM isozyme (MM-CK). CK in these cells concurs with that which is coupled to Na,K-ATPase in other cells and is considered to supply ATP for the Na,K-ATPase that mediates the high KCl of endolymph. Inner hair cells revealed content of the BB isozyme and in this respect resembled the energy-transducing photoreceptor cells in retina. In addition, outer phalangeal (Deiters') cells stained for both MM- and BB-CK whereas inner phalangeal cells evidenced content of only the BB isozyme. Immunolocalization of CK appeared similar in mouse and gerbil inner ear. Specificity of the staining was affirmed by observations in agreement with those reported for CK in various cell types and by staining with antisera from more than one source.
Insights
Creatine kinase (CK) is abundant in specific inner ear cells, supplying energy for ion transport. This study maps CK isozymes in gerbil and mouse inner ear epithelium, revealing distinct patterns in cochlear and vestibular cells.
Area of Science:
- Otolaryngology
- Cell Biology
- Biochemistry
Background:
- The inner ear epithelium maintains endolymph homeostasis, crucial for hearing and balance.
- Na,K-ATPase activity is vital for generating the unique ionic composition of endolymph.
- Creatine kinase (CK) is an enzyme system involved in cellular energy buffering.
Purpose of the Study:
- To immunocytochemically localize creatine kinase (CK) isozymes within the inner ear epithelium of gerbils and mice.
- To investigate the potential role of CK in providing ATP for Na,K-ATPase in specific inner ear cell types.
Main Methods:
- Immunocytochemistry was employed to detect CK isozymes (MM-CK and BB-CK) in gerbil and mouse inner ear tissues.
- Antisera from multiple sources were used to ensure the specificity of CK staining.
- Localization patterns were compared between different cell types and species.
Main Results:
- Marginal cells of the stria vascularis, dark cells, and transitional cells showed abundant MM-CK.
- Inner hair cells contained BB-CK, similar to retinal photoreceptor cells.
- Outer phalangeal (Deiters') cells stained for both MM-CK and BB-CK, while inner phalangeal cells only showed BB-CK.
- CK localization patterns were consistent between mouse and gerbil inner ears.
Conclusions:
- CK isozymes are differentially localized in the gerbil and mouse inner ear epithelium.
- MM-CK in stria vascularis and vestibular dark/transitional cells likely supports Na,K-ATPase function for endolymph homeostasis.
- BB-CK in inner hair cells suggests a role in energy metabolism, potentially supporting sensory transduction.