We developed the real-time PCR quantification of endothelin-A (ET-A) and endothelin-13 (ET-B) receptor genes and present their relative expression levels in various adult tissues and during development in mouse using the 2(-Delta Delta C(T)) method. ET-A and ET-B receptors were detected in all tissues examined. Gene expression of ET-A and ET-B receptors increases during the later stages of embryonic development in lung, heart, liver, kidney, and skin and reaches a maximum on the first one or two days after birth. The results, in agreement with our data on endothelin (ET) ligands, suggest that the ET system may be involved in the emergence and maintenance of functions vital after birth in these organs. These findings were corroborated through observation of the correlation between the gene expression and (poly)peptide production of the ET system in normal skin before and after parturition. (C) 2003 Elsevier Science (USA). All rights reserved.