Structure-activity relationships of vasopressin analogues on release of factor VIII in dogs

In order to study structure-activity relationships as to Factor VIII release conscious dogs were injected with analogues of vasopressin. The peptides used were chemically modified either in the hexapeptide ring structure of the vasopressin molecule or in the C-terminal tripeptide or in both. The results showed that an intact C-terminal appears to be of importance for retaining Factor VIII releasing activity of the analogues, whereas at least some modifications of the ring structure are tolerated without loss of activity. Decreased activity was also observed when the disulphide bridge was substituted with a monocarba bond.