Ammonium transport in the kidney: new physiological concepts and their clinical implications.

This article is based on a Basic Science Symposium presented at the 23rd Annual Meeting of the American Society of Nephrology. New information on the segmental transport of ammonium by the proximal tubule, the thick ascending limb of Henle's loop, and the collecting duct is integrated into a thesis that NH4+ excretion is controlled by the rate of production, by diffusion of NH3 along gradients established by proton secretion, and by active transport of NH4+. These new concepts are applied to a novel explanation of the pathogenesis of distal renal tubular acidosis.