Endothelin receptors in rat pituitary gland.

1. We used the quantitative receptor autoradiographic method plus 125I-endothelin-1 (125I-ET-1), BQ-123, a specific antagonist for the endothelin ETA receptor, and sarafotoxin S6c, a selective agonist for the ETB receptor to investigate the ET receptor in the rat pituitary gland. 2. The method revealed that the BQ-123-sensitive ETA receptor was present predominantly in the anterior lobe and Rathke's pouch. 3. The posterior lobe contained BQ-123-sensitive ETA and sarafotoxin S6c-sensitive ETB receptors, in almost the same proportion. There was no significant 125I-ET-1 binding to the intermediate lobe. 4. Knowledge of the heterogeneous distribution of ET receptor subtypes in the pituitary gland supplies information that will be pertinent to physiological investigations of the gland.