ENDOTHELIN RECEPTOR-B EXPRESSION IN THE RAT AND RABBIT LUNG AS DETERMINED BY IN-SITU HYBRIDIZATION USING NONISOTOPIC PROBES

Endothelins are a family of potent vasoactive peptides. Full-length cD NA clones to human endothelin receptor B (ET(B)) mRNA were random prim e-labeled with nucleotides conjugated to digoxigenin for in situ hybri dization. The labeled cDNA was used to probe frozen sections of rat an d rabbit lung. Detection of the digoxigenin-labeled probe was accompli shed by an antibody-enzyme conjugate, anti-digoxigenin alkaline phosph atase. The location of the antibody-antigen complex was visualized as an enzyme-linked color reaction. The hybridization, washings, and dete ction steps were performed under stringent conditions. The following c ell types of the rat and rabbit lung had abundant positive reaction pr oduct to the ET(B) probe: bronchiolar and bronchial epithelium, endoth elium of smooth-muscle-walled vessels, and bronchial and bronchiolar-a ssociated lymphoid tissue. Abundant positive reaction product was also observed in cell populations in the lung parenchyma. Additional studi es are being performed to identify those populations. The results of t his study suggest that in addition to vasoactivity, endothelins play o ther important roles in the lung.