Ubiquitous presence of chromogranin A in the inner ear of guinea pig

Chromogranin A (CGA), which is supposed to be responsible for the calcium storage of secretory vesicles and is also considered to be a marker protein of neurons and endocrine cells, has been found in a variety of organs and tissues. In the present study, soluble proteins from the organ of Corti, saccule, crista, utricle, tectorial membrane, stria vascularis, and the spiral ligament from the inner ear of guinea pig were extracted, and probed with both polyclonal and monoclonal CGA antibodies to determine the presence of CGA. A 75 kDa protein reactve to both antibodies was found in the organ of Corti, saccule, crista, utricle, stria vascularis, and the spiral ligament, suggesting the widespread presence of CGA in the inner ear.