title: Mechanisms of K+ transport in isolated turtle urinary bladder. Induction of active K+ secretion in a K+-absorbing epithelium.
abstract: Transepithelial K(+) movement was studied in vitro in the short-circuited turtle bladder by increasing luminal K(+) permeability and by inhibiting the basolateral Na/K pump. Luminal addition of amphotericin B caused net K(+) secretion (180+/-52 nmol/h) compared with net K(+) absorption (42+/-6 nmol/h) in control bladders. Serosal ouabain and luminal amiloride abolished K(+) secretion in amphotericin-treated bladders; ouabain restored net absorption (45+/-16 nmol/h). The direction and rate of net K(+) transport are controlled by the relative K(+) permeabilities and the Na/K pump sites at the two cell membranes of the epithelium.
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D004848:Epithelium / Q000502:physiology; D007473:Ion Channels / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D014426:Turtles; D001743:Urinary Bladder / Q000502:physiology*
chemical_list: D007473:Ion Channels; D000584:Amiloride; D000666:Amphotericin B; D012964:Sodium; D011188:Potassium