Glomerular mesangial and endothelial cells have been reported to synthesize and secrete endothelin-1 (ET-1). Whether glomerular epithelial cells (GEC) have the ability to synthesize ET-peptides is not known. Employing immunocytochemistry we report that the GEC in vitro constitutively express ET-1 and ET-3. ET-1 synthesis by the GEC was further confirmed by detection of a specific 2.3kb mRNA that hybridizes with rat prepro ET-1 genomic DNA on Northern blot analysis. ET-1 is secreted into the medium in a time-dependent manner as measured by radioimmunoassay and radiobinding assay. Synthesis of endothelin peptides by the GEC may have important implications in the pathogenesis of glomerular diseases where GEC injury figures prominently.
