The Renal Regulation of Acid-Base Balance in Man. I. The Nature of the Mechanism for Acidifying the Urine 1

The Renal Regulation of Acid-Base Balance in Man. Ii. Factors Affecting the Excretion of Titratable Acid by the Normal Human Subject 1

“…Deviation from a linear relationship indicates that the kidney of the dog is unable to elaborate as acid a urine at high rates of phosphate excretion as at low rates. This fact is in accord with the statement in the preceding paper (1), that the renal tubular capacity of the dog to acidify the urine is less than that of man. The proportionality between the rate of excretion of acid and the rate of excretion of buffer which is evident in Figure 1.…”

“…Transformation of the slightly alkaline glomerular filtrate into acid urine has been assigned in man (1 ) as in the dog (2) to the exchange of hydrogen ions formed within the tubular cells for ions of fixed base in the tubular urine. The most acid urine which the kidney can form is of pH 4.5 to 4.7 (1,3).…”

“…The most acid urine which the kidney can form is of pH 4.5 to 4.7 (1,3). At this reaction negligible quantities of strong acids such as hydrochloric or sulfuric can exist in free form.…”

Renal Excretion of Inorganic Phosphate in Newborn Infants 12

“…Because of the important role phosphate plays in many body functions and since phosphate absorbed in excess of body needs is excreted mainly by the kidneys, detailed studies of renal excretion of phosphate have been made in dogs and in adult human subjects, especially by Pitts and his coworkers (1)(2)(3). Mechanisms involved in renal excretion of phosphate in young infants are of interest for additional reasons.…”

Homeostasis, the Milieu Intérieur, and the Wisdom of the Nephron

“…Although some acid-base enthusiasts enjoy consideration of the "strong ion difference" to reconcile data, the normal kidney's remarkable response to subtle differences in pH or, more likely, intracellular CO 2 does not take these differences into account. Although the exact mechanisms used to sense pH are still not yet understood, it is well known that the kidney plays a dominant role in the regulation of the acid-base balance (47). Indeed, with acidosis, a complex intracellular cascade ensues, including activation of the electroneutral sodiumcoupled amino acid transporter for glutamine, an increase in glutamine metabolism and ammoniagenesis, as well as an increase in the expression of the sodium hydrogen antiporter (48,49).…”