Effect of amphotericin B on permeability and short-circuit current in toad bladder

Abstract

The effects of amphotericin B on the isolated urinary bladder of the toad, Bufo marinus, were studied. Amphotericin B caused a significant and reversible rise in the osmotic permeability to water. The response was not prevented by 10-3 [image] dinitrophenol, but was prevented by the simultaneous addition of ergosterol. Prior treatment of the bladder with amphotericin B inhibited the increase in the osmotic flow of water caused by the subsequent addition of vasopressin and cyclic 3[image],5[image]-AMP. The polyene antibiotic did not increase the short-circuit current of bladders studied shortly after removal from the toad, but did after overnight incubation in the presence of glucose. In contrast, the significant rise in the passive permeability to water and urea following exposure to the drug, was independent of the time of the experiment. The results are not consistent with the previously held view that this agent acts at a single site in the toad bladder and preclude interpretations based on results with amphotericin B concerning the site and mode of action of other agents or experimental manipulations which affect the permeability of this structure.