Mechanism of the inhibitory action of oxytocin on transport of isotonic fluid through the gall bladder epithelium

The effect of oxytocin on the intensity of absorption of Ringer's solution by the epithelium of the isolated frog gall bladder and on the total Mg-, Na-, K-ATPase activity in its cells was studied. In doses of 0.5–20 m.u/ml, added on the side of the serosal surface of the organ, oxytocin reduced the intensity of isotonic fluid transport and the Na, K-ATPase activity of the epithelial cells of the gall bladder; Mg-ATPase activity was unchanged under these conditions. With an increase in the oxytocin concentration the values of the parameters studied fell exponentially. It is concluded that inhibition of the transport function of the gall bladder epithelium by oxytocin is connected with its inhibitory action on the Na, K-ATPase of the epithelial cells.