Binding Sites for ¹²⁵I-Labelled Endothelin-1 in the Kidneys: Differential Distribution in Rat, Pig and Man Demonstrated by Using Quantitative Autoradiography

1. Quantitative receptor autoradiography in vitro has been used to determine the distribution and density of specific binding sites for ¹²⁵I-labelled endothelin-1 in human, porcine and rat kidneys. Immunocytochemistry was used to visualize von Willebrand factor-positive endothelial cells in adjacent sections to those used for autoradiography.

2. High levels of specific binding were detected in the vasa recta and papilla of all three species with lower levels in the medulla and cortex.

3. A major difference between the species was observed within the glomeruli, where high levels of binding were found in the rat but no detectable binding sites in pig or man.