title: Low micromolar concentrations of cadmium and mercury ions activate peritubular membrane K+ conductance in proximal tubular cells of frog kidney.
abstract: The present study was designed to investigate the acute effects of extracellular low micromolar concentrations of cadmium and mercury ions on the peritubular cell membrane potential and its potassium selectivity in proximal tubular cells of the frog kidney. Peritubular exposure to 3 micromol/L Cd(2+) or 1 micromol/L Hg(2+) led to a rapid, sustained and reversible hyperpolarization of the peritubular cell membrane, paralleled by an increase in fractional K(+) conductance. Peritubular barium abolished hyperpolarization of the peritubular cell membrane to peritubular 3 micromol/L Cd(2+) or 1 micromol/L Hg(2+). Perfusing the lumen with 10 mmol/L l-alanine plus/minus 3 micromol/L Cd(2+) or Hg(2+) did not modify rapid depolarization and rate of slow repolarization of the peritubular cell membrane potential. In conclusion, low micromolar concentrations of Cd(2+) and Hg(2+) increase K(+) conductive pathway in the peritubular cell membrane and in this way can enhance ability of proximal renal tubular cells to maintain the driving force for electrogenic Na(+) and substrate reabsorption.
authors.affiliation: Department of Pathological Physiology, Medical Faculty, Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Nesovic-Ostojic
authors.forename: Dusan
authors.initials: D
authors.lastname: Cemerikic
authors.forename: Simon
authors.initials: S
authors.lastname: Dragovic
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Milovanovic
authors.forename: Jovica
authors.initials: J
authors.lastname: Milovanovic
mesh_terms: D000409:Alanine / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002104:Cadmium / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D007477:Ions / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D008628:Mercury / Q000737:chemistry / Q000494:pharmacology*; D009994:Osmolar Concentration; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011893:Rana esculenta / Q000502:physiology*
chemical_list: D007477:Ions; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D002104:Cadmium; D001464:Barium; D008628:Mercury; D000409:Alanine