Procainamide uptake by rabbit proximal tubules.
Procainamide is an organic cation and commonly prescribed drug that is actively secreted into the urine by renal proximal tubules. In order to elucidate further the mechanisms involved in this secretion, [3H]procainamide uptake into dissected S2 segments of superficial proximal tubule cells was studied. Uptake of [3H]procainamide was reduced by hypothermia and in a dose-related manner by the organic cations nonradiolabeled procainamide, cimetidine and quinidine and also by the carbonic anhydrase inhibitors acetazolamide and benzolamide, but not by ouabain. All these drugs were shown previously to inhibit transtubular secretion of [3H]procainamide in isolated perfused proximal tubules. The results of these and our previous studies suggest that 1) organic cations reduce the tubular secretion of each other, in part, by competing for uptake across the basolateral membrane of renal tubule cells, 2) acetazolamide and benzolamide reduce urinary excretion of organic cations, in part, by inhibiting proximal tubular secretion and 3) the potential difference across the basolateral cell membrane (due to activity of Na+-K+-dependent adenosine triphosphatase) is not the only driving force for uptake of organic cations into intact renal tubule cells.
D000818:Animals; D002412:Cations / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D005260:Female; D007035:Hypothermia / Q000378:metabolism; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D011342:Procainamide / Q000378:metabolism*; D011817:Rabbits
D002412:Cations; D002927:Cimetidine; D011342:Procainamide