[Effect of noradrenaline on ion and water transport through frog gall bladder epithelium].

In experiments on isolated gallbladders (GB) of frogs it was established that noradrenaline in concentration of 6.10(-9)--3.10(-4) M acting on the organ from the serosalsurface causes firstly a short increase and then -- a prolonged inhibition of the absorption rate of NaCl -- isotonic fluid from the gall bladder cavity. While the concentration of the mediator increases in the inculation medium, its inhibiting effect increases too. Depression, and at high concentration in the medium, full inhibition of the process of fluid absorption is accompanied with distinct decrease of Na--, K--ATPase activity of gall bladder epithelial cells. Mediator in concentration of 3.10(-8) M caused an increase of membrane potential of the epithelial cells, while its increasing in the inculation medium to 3.10(-6) M caused a decrease of the transmembrane potential difference. Under the noradrenaline influence the increase of the osmotic permeability of the gall bladder's wall for the water flow directed from the mucosa to the serosalsurface of the organ took place, and also the decrease of the wall's permeability for the water flow in the opposite direction was seen. It was concluded that the noradrenaline inhibitory action on the process of absorption of NaCl--isotonic fluid from the gall bladder cavity was observed because of the decrease of the Na--K--ATPase activity, and also because of the change of the permeability of epithelium for the passive ion and water transport.