The relationship between cochlea and kidney

Abstract

Abstract The not uncommon association in clinical practice of problems existing simultaneously in the kidney and ear, prompted a closer look at these two distant organs, revealing in fact that they may be comparable in a variety of ways. Anatomical similarities were seen especially at the ultra‐structural level. Physiological mechanisms of fluid and electrolyte balance are present in both organs, and this common function is reflected in similar pharmacological actions of certain drugs. Congenital syndromes which have both renal and hearing defects have been the subject of much investigation attempting to relate a single etiological process in a common pathogenesis. To investigate a possible existence of shared antigenicity the tools of immunochemistry and immunohistochemistry were employed in experimental studies comparing the kidney with the lateral cochlear wall. The experimental animals chosen were the rat and guinea pig. Anti‐rat sera and anti‐guinea pig sera were produced using the goat or rabbit respectively as the antibody producing animal. In order to produce the antisera, specimens of stria vascularis were dissected from the cochlea. The collected specimens were then placed in saline and Complete Freunds Adjuvant, emulsified and then injected into subcutaneous sites of rabbits. After about 10 days the blood was withdrawn and the serum extracted from the blood. This crude serum was then used in subsequent experiments as the anticochlea antibody (AC Ab). In a similar manner glomerular basement membrane antibody was prepared (AGBM Ab). Two methods of immunofluorescent staining were used, namely, the indirect and direct method. In the indirect method, frozen sections of normal cochlea or renal tissue specimens were treated with the previously prepared AC Ab or AGBM Ab and then counterstained with Fluorescein labeled goat anti‐rabbit gamma globulin serum (GARG‐Fl). In the direct method tissue specimens from guinea pigs that had been injected with either AC Ab or AGBM Ab were stained directly with GARG‐Fl. In a third part of the experiments, the left cochlea from each animal injected with either AGBM Ab or AC Ab was taken for light histology. The results of these experiments are summarized in Tables I, II, and III. Of marked significance in our studies is the observation that AC Ab is capable of staining renal tubular epithelium. This presents compelling evidence of antigenically similar epithelial components. In conclusion, there is a fascinating similarity between the cochlea and the kidney. This similarity extends through a variety of modalities. There is even experimental evidence of a possibility of antigenically similar epithelial components.