title: Chloride activity in cells of isolated perfused cortical thick ascending limbs of rabbit kidney.
abstract: Rabbit cortical thick ascending limb segments were perfused in vitro, and intracellular Cl- activity was estimated in three types of experiments using conventional and chloride selective microelectrodes. In series 1 Ringer like solutions were present on the two epithelial sides. In series 2 limen Cl- was replaced by gluconate, and in series 3 furosemide, 10-20 . 10(-6) mol . 1-1, was added to the lumen perfusate. It was found that under control conditions intracellular Cl- activity, as estimated from the difference of the reading of the conventional (n = 53) and ion selective electrodes (n = 118) was 26 +/- 1 mmol . 1-1. Thi value is approximately three times higher than expected for passive distribution of Cl-. After removal of lumen Cl- (series 2) intracellular Cl- activity fell to 9 mmol . 1(-1) which is only some 4 mmol . 1(-1) above passive distribution. We argue that these 4 mmol . 1(-1) reflect mainly the interference with the Cl- electrode by other anions, such as phosphate. The above estimates for intracellular Cl- activity, have to be diminished by these 4 mmol . 1(-1), and, thus, are close to 22 mmol . 1(-1). In series 3 a rapid and reversible fall in intracellular Cl- from 23 to 7 mmol . 1(-1) was observed. We conclude that the Cl- activity in cTAL cells is clearly above equilibrium under control conditions and that it falls rapidly to values close to equilibrium when Cl- reabsorption is blocked by either removing lumen Cl- or by blocking the Cl- entry via the Na+-2 Cl--K+-carrier with furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D002713:Chlorine / Q000378:metabolism*; D046508:Culture Techniques; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D005942:Gluconates / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007684:Kidney Tubules / Q000166:cytology*; D008138:Loop of Henle / Q000166:cytology* / Q000378:metabolism; D010477:Perfusion; D010756:Phosphoric Acids / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology; D012996:Solutions
chemical_list: D002712:Chlorides; D005942:Gluconates; D010756:Phosphoric Acids; D012996:Solutions; D002713:Chlorine; D005665:Furosemide; D012964:Sodium; D005947:Glucose; D011188:Potassium; D002118:Calcium