An Inhibitor of Oxytocin from the Urinary Bladder of the Toad, Bufo marinus

Abstract

A PREVIOUS investigation has shown that the isolated bladder of the toad, B. marinus, releases an inhibitor of oxytocin into the bathing Ringer's solution¹. More recently a similar inhibitor has been invoked to explain the inhibition of the effects of vasopressin and of adenosine-3′, 5′-monophosphate on the toad bladder². In the former investigation it was shown that inhibitor could be obtained by gently stirring isolated toad bladders in a modified Ringer's solution, and that the inhibitor so obtained was not readily dialysable. In the investigation reported here the previous results were confirmed; however, it was found that, following heat-treatment of the inhibitor solution, the inhibitor became dialysable. We report a modified preparation of the inhibitor based on this finding.