The uterus-stimulating activity of the plasma of male rabbits before and after mating.

Abstract

This investigation was carried out to study the uterus-stimulating activity of the plasma of male rabbits before and after mating to see whether there was any change. Twenty experiments were performed where blood from the male rabbit was collected by means of intracardiac puncture before and 2½ min. after mating. Ice-cold polythene syringes and tubes were used for the collection of blood, and the plasma was assayed on the isolated rat uterus (Holton, 1948). The oxytocic activity was assayed against synthetic oxytocin or against a freshly prepared solution of 5-hydroxytryptamine (5-HT) in two groups of ten rabbits each. In five out of ten experiments in each group, the rat uterus in a 10 ml. bath was treated with 50 μg. dichloroisoproterenol (DCI) for 20 min. to ensure that adrenaline in the plasma would not interfere with the assay (Levy & Tozzi, 1963). In those experiments where the plasma was assayed