In vitro CRF activity of vasopressin analogs is not related to pressor activity.

The relative abilities of four vasopressin analogs to stimulate the release of beta-endorphin-like immunoreactivity from rat anterior pituitary quarters in vitro were found by the present study to be somewhat related to their relative antidiuretic activities, but to be very different from their relative pressor potencies. We conclude that vasopressin exerts its direct beta-endorphin-releasing activity via receptors with conformational requirements which are different from those of the vascular receptor type.