A HISTAMINE-LIKE SUBSTANCE IN THE POST-PARTUM RABBIT UTERUS

Abstract

Saline extracts of post-partum rabbit uteri, taken within 12 hrs. after delivery, contain a toxic substance lethal to non-pregnant animals. With one exception, the toxic factor was not present in non-pregnant uteri or in skeletal muscle, blood serum, or whole blood of rabbits in late stages of pregnancy or 1 day post-partum. Animals one day pre-partum to 1 day post-partum are no less susceptible to the toxic factor than are non-pregnant animals. The toxic factor is probably histamine or a histamine-like substance. It resembles histamine in physiological properties and is readily inactivated by incubation with histaminase. The presence of histamine or a histamine-like material in the full term and post-partum rabbit uterus is discussed in relation to events leading to parturition, i.e., color change, edema, muscle contractions and post-partum hemorrhage.