INACTIVATION OF ANTIDIURETIC HORMONE AND OXYTOCIN DURING PREGNANCY

¹ The Clinical Endocrinology Research Unit, Medical Research Council, University of Edinburgh

1. When oxytocin and vasopressin are incubated at 37° C. for two hours with suitable volumes of plasma from healthy pregnant women, or with saline extracts of normal or pre-eclamptic placentæ, they are destroyed.

2. The loss of both oxytocic and antidiuretic activity is thought to be due to an enzyme which is heat labile with an optimum pH between 7 and 8.

3. Placentæ from healthy pregnant women contain more enzymatic activity than placentae from women with pre-eclamptic toxæmia.

Note:

I wish to thank Professor J. H. Gaddum and Professor R. J. Kellar for their helpful advice and criticism, also Dr. G. D. Matthew and Dr. T. N. MacGregor for providing clinical material. I also wish to thank Miss Muriel Burnett for technical assistance, and the National Health and Medical Research Council (Australia) for a travel grant.