Active substance from the serum of laying hens and its effect on uterine smooth muscles

Blood serum from laying hens has an excitatory effect on isolated uterine smooth muscles of laying hens. This excitatory effect is not observed for the blood serum of pullets and cocks. After ultrafiltration and gel filtration on Sephadex G25, it was found that the excitatory effect of the blood serum was due to a low-molecular substance (m.w. below 5000 Da). The effect of this active substance was found to be inhibited by indomethacin, brufen and SC 19220. The presence of this substance in the serum of laying hens and its contractile effects, which are probably associated with prostaglandin mechanisms of regulation in the uterine smooth muscles, suggests that it is associated in the processes of oviposition in hens.