[2-o-Iodotyrosine]-oxytocin and [2-o-methyltyrosine]-oxytocin: basic pharmacology and comments on their potential use in binding studies.

Both [2-o-iodotyrosine]-oxytocin and [2-o-methyltyrosine]-oxytocin display only weak vasopressor and antidiuretic effects on rats. They inhibit the in vitro uterotonic action of oxytocin; this inhibition is not fully competitive. It is concluded that they are not suitable as markers for studies of uterine receptor for oxytocin.