The kidney and acid-base regulation

2009 ◽  
Vol 33 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Bruce M. Koeppen

Since the topic of the role of the kidneys in the regulation of acid-base balance was last reviewed from a teaching perspective (Koeppen BM. Renal regulation of acid-base balance. Adv Physiol Educ 20: 132–141, 1998), our understanding of the specific membrane transporters involved in H+, HCO3−, and NH4+ transport, and especially how these transporters are regulated in response to systemic acid-base disorders, has advanced considerably. In this review, these new aspects of renal function are presented, as are the broader and more general concepts related to the role of the kidneys in maintaining the acid-base balance. It is intended that this review will assist those who teach this aspect of human physiology to first-year health profession students.

1989 ◽  
Vol 257 (2) ◽  
pp. F170-F176 ◽  
Author(s):  
J. C. Brown ◽  
R. K. Packer ◽  
M. A. Knepper

Bicarbonate is formed when organic anions are oxidized systemically. Therefore, changes in organic anion excretion can affect systemic acid-base balance. To assess the role of organic anions in urinary acid-base excretion, we measured urinary excretion in control rats, NaHCO3-loaded rats, and NH4Cl-loaded rats. Total organic anions were measured by the titration method of Van Slyke. As expected, NaHCO3 loading increased urine pH and decreased net acid excretion (NH4+ + titratable acid - HCO3-), whereas NH4Cl loading had the opposite effect. Organic anion excretion was increased in response to NaHCO3 loading and decreased in response to NH4Cl loading. We quantified the overall effect of organic ion plus inorganic buffer ion excretion on acid-base balance. The amounts of organic anions excreted by all animals in this study were greater than the amounts of NH4+, HCO3-, or titratable acidity excreted. In addition, in response to acid and alkali loading, changes in urinary organic anion excretion were 40-50% as large as changes in net acid excretion. We conclude that, in rats, regulation of organic anion excretion can contribute importantly to the overall renal response to acid-base disturbances.


1986 ◽  
Vol 64 (5) ◽  
pp. 1054-1057 ◽  
Author(s):  
B. L. Tufts ◽  
D. P. Toews

Specimens of Bufo marinus (L.) were cannulated in both ureters to partition between the regulatory contributions of the kidney and urinary bladder. These bladder-bypassed animals were then exposed to 10 h of dehydration in air and renal function and acid–base balance were assessed. The results indicated that the kidney showed an almost immediate response to dehydration which consisted of a large glomerular and smaller tubular component. Bypassing and emptying of the bladder and the removal of the ambient water had no effect on the animal's ability to maintain normal acid–base balance.


1989 ◽  
Vol 257 (4) ◽  
pp. F696-F699
Author(s):  
T. Almdal ◽  
H. Vilstrup ◽  
K. Bjerrum ◽  
L. O. Kristensen

It has been suggested that urea synthesis participates directly in body pH homeostasis by removal of bicarbonate. To elucidate this hypothesis sodium bicarbonate or sodium chloride was infused (11.5 mumol/min) for 90 min into control rats and into rats that had undergone an 85% hepatectomy immediately before starting the infusion. Urea synthesis rate was 2.6 +/- 0.3 mumol/min (mean +/- SE) in controls, and was significantly (P less than 0.01) reduced to 1.0 +/- 0.2 mumol/min in partially hepatectomized rats. At the start of bicarbonate infusion, pH was 7.38 and 7.34 in control and partially hepatectomized rats, respectively, and at the end of infusion, pH was 7.56 and 7.51. Standard bicarbonate at start of bicarbonate infusion was 21.9 and 21.3 mM in controls and partially hepatectomized, respectively, and it increased to 32.7 and 29.9 mM at end of infusion. In saline-infused rats a slight decrease of approximately 0.05 pH units was observed during the experiment, but again no difference emerged between control and partially hepatectomized rats. It is concluded that a major role of the liver in the regulation of acid-base balance is unlikely.


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