Binding of (3H)-piretanide to a specific receptor of renal medulla.

We had previously demonstrated that (3H)-piretanide binds to a receptor located on medullary membranes of canine kidney. Here we show that binding is specific for a particular group of loop diuretics. Sulfonamide diuretics of the benzoic acid family, other substituted sulfonamides, and phenoxy-acetic acid derivates displace (3H)-piretanide from its receptor. Loop diuretics that do not act at the luminal tubular membrane do not displace piretanide, nor do diuretics with a different site and mode of action (thiazides; inhibitors of the Na+/H+ antiporter (amiloride), of Na+K+ ATPase (ouabain), or of carbonic anhydrase (acetazolamide). We demonstrate that no interference occurs between the piretanide receptor and membrane bound receptors of several neurotransmitters.