title: The electrical properties and active ion transport across the urinary bladder of the urodele, Amphiuma means.
abstract: 1. The electrical properties and the active transport processes of the isolated urinary bladder of the urodele, Amphiuma means, were studied by mounting this tissue as a flat sheet between two halves of a lucite chamber. The mean transepithelial potential difference was 70-2 +/- 2-3 mV (serosa positive), the mean short-circuit current was 10-9 +/- 0-5 micrionA/mg of dry weight and the mean transepithelial d.c. resistance was 6540 +/- 374 omega mg of dry weight. 2. The short-circuit current (Isc) accounted for 92% of the net 22Na+ flux from the mucosa to the serosa. The difference resulted from a transport of 36Cl- in the same direction as sodium. 3. The active sodium transport exhibited typical saturation kinetics, having a Km of 15-4 m-equiv/l. and approaching zero order at 60-70 m-equiv/l. The transepithelial potential difference increased linearly with the log of the mucosal sodium concentration at a rate of 50-3 mV per tenfold concentration change. 4. In the absence of the major anions (HCO3- and Cl-) from the bathing solutions, the electrical properties and the sodium influx decreased to less than 40% of their control values. The presence of only one of these two anions in the serosal bathing solution was sufficient to maintain these parameters. 5. Amiloride (10(-5)M) and ouabain (10(-6)M) inhibited the sodium transport 97% and 85% respectively. Amphotericin B (10(-6)M) stimulated the sodium transport 47%. Furosemide (10(-3)M) inhibited the chloride transport 43%. The sodium transport was insensitive to the action of two enurohypophyseal peptides tested, lysine-vasotocin and pitocin.
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000663:Amphibians / Q000502:physiology*; D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active; D002712:Chlorides / Q000378:metabolism; D004594:Electrophysiology; D004848:Epithelium / Q000502:physiology; D005665:Furosemide / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008236:Lypressin / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
chemical_list: D002712:Chlorides; D010121:Oxytocin; D008236:Lypressin; D010042:Ouabain; D000584:Amiloride; D005665:Furosemide; D000666:Amphotericin B; D012964:Sodium