title: Dose-related effects of furosemide, bumetanide, and piretanide on the thick ascending limb function in the rat.
abstract: To assess the action of piretanide, bumetanide, and furosemide on the thick ascending limb of Henle's loop, perfusion experiments were performed on rat kidneys, using a recently developed conductivity microprobe for the analysis of distal tubular fluid. Surface nephrons were perfused downstream from a solid paraffin block through Henle's loop with isotonic saline solution containing either 10(-6), 3 X 10(-6), or 10(-5) mol/L piretanide, bumetanide, or furosemide, respectively. For control values, diuretic-free saline was used. Conductivity measurements of early distal tubular fluid were performed in situ with a conductivity microprobe and were recorded continuously during variations of loop perfusion rate. A recently described micro-stop-flow technique was used to measure the conductivity of fluid emerging from the ascending limb, thereby evaluating the amount of sodium chloride reabsorbed. A significant electrolyte transport inhibition occurred within the concentration range between 10(-6) and 10(-4) M. Bumetanide and piretanide were slightly more effective than furosemide. Luminal diuretic concentrations of 10(-6) M or below were without influence on electrolyte reabsorption. Concentrations of 10(-4) M resulted in complete inhibition of the diluting segment electrolyte transfer.
mesh_terms: D000042:Absorption; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology*; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005665:Furosemide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007684:Kidney Tubules / Q000187:drug effects*; D008138:Loop of Henle / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D004232:Diuretics; D013449:Sulfonamides; D002034:Bumetanide; D012965:Sodium Chloride; D005665:Furosemide; C015451:piretanide; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium