Immunochemical characterization and localization of endothelin ETB receptor

A highly specific antiserum was raised against purified bovine endothelin ETB receptor and used to determine the tissue distribution of the receptor subtype ETB and to localize the receptor immunohistochemically in the kidney, adrenal gland, lung, cerebellum, and pituitary gland whose functions are known to be under strong influence of endothelin. The antiserum raised in a rabbit specifically recognized the receptor band on Western blot analysis of membrane proteins. Furthermore, it immunoprecipitated only ETB, establishing its ETB specificity. By determination of the percentage of the total number of the endothelin receptors that is immunoprecipitable with the antiserum, the amounts of the ETB relative to those of the ET receptors were found to vary from tissue to tissue: lung (70%), cerebellum (55%), pituitary gland (50%), kidney (25%), adrenal gland (10%), and testis (< 2%). This means that, in the lung, ET is the major form, whereas in the testis, ETA is predominant, comprising >95% of the receptors. Immunohistochemical examination of tissue sections revealed endothelium localization of the ETB endothelin receptor.