An Update on Kidney Ammonium Transport Along the Nephron

Harris, Autumn N.; Shankar, Mythri; Melanmed, Michal; Batlle, Daniel

doi:10.1053/j.akdh.2022.12.005

Cited by 10 publications

(8 citation statements)

References 77 publications

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“…Glutamine is the primary substrate for ammoniagenesis in the proximal tubule. At this stage, bicarbonate reabsorption is mediated by a specific transporter (electrogenic sodium bicarbonate cotransporter isoform 1A; NBCe-1 A) [ 8 ]. These receptors are present exclusively in the proximal tubule, and they play a key role in bicarbonate reabsorption.…”

Section: Discussionmentioning

confidence: 99%

Serum Bicarbonate Deficiency in Dogs with Acute and Chronic Kidney Disease

Lippi

Perondi

Gori

et al. 2023

Veterinary Sciences

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Serum bicarbonate deficiency is a disorder frequently found in human patients with acute (AKI) and chronic (CKD) kidney disease, due to abnormalities in kidney generation and reabsorption of bicarbonate. Although alkali supplementation is usually performed in both humans and veterinary CKD patients, data regarding the frequency of bicarbonate disorders in AKI and CKD dogs are scarce. The aim of the present study is to assess the frequency and the severity of bicarbonate deficiency of dogs affected by AKI, acute chronic kidney disease (ACKD), and CKD, and to investigate its possible association with the IRIS grade/stage as well as with disorders of calcium phosphate metabolism. A retrospective evaluation of the serum biochemical panels of all dogs with diagnoses of AKI, ACKD, and CKD referred to the nephrology and urology service of the Veterinary Teaching Hospital of the University of Pisa, between January 2014 and January 2022, was performed. Bicarbonate deficiency was defined as serum bicarbonate < 22 mmol/L and classified as moderate (between 18 and 22 mmol/L) or severe (<18 mmol/L). Serum bicarbonate deficiency was found in 397/521 dogs (76%), of which 142/397 (36%) showed moderate deficiency, and 255/397 (64%) severe deficiency. Dogs with AKI and ACKD showed a significantly higher frequency of bicarbonate deficiency (p = 0.004) and severe forms compared to CKD dogs (p = 0.02). In AKI and ACKD dogs, a negative linear correlation was found between serum bicarbonate and serum creatinine, urea, and phosphate. The frequency of bicarbonate deficiency was higher in the later stages of the disease in both AKI (p = 0.01), ACKD (p = 0.0003), and CKD dogs (p = 0.009). Dogs with serum CaxP ≥ 70 mg2/dL2 showed a higher frequency of bicarbonate deficiency (p = 0.01) and showed severe forms (p = 0.01) compared to dogs with CaxP < 70 mg2/dL2. Serum bicarbonate deficiency seems to be a very frequent disorder in both AKI, ACKD, and CKD dogs, with an increasing frequency and severity in more advanced stages of kidney disease. The higher frequency and severity of bicarbonate deficiency in AKI and ACKD may be caused by a more severe and sudden loss of kidney function, or extra-renal factors. Finally, the association between frequency and severity of bicarbonate deficiency and abnormal CaxP may suggest a potential connection between metabolic acidosis and bone mineral disorders.

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Section: Discussionmentioning

confidence: 99%

Serum Bicarbonate Deficiency in Dogs with Acute and Chronic Kidney Disease

Lippi

Perondi

Gori

et al. 2023

Veterinary Sciences

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“…The total amount of amino acids in the renal filtrate is reabsorbed in PCT and partially metabolized (mainly glutamine) producing ammonia and bicarbonate. Glutamine transport and metabolism are coupled to proton excretion ( Harris et al, 2023 ). The glutamine transfer by apical Na + -dependent neutral amino acid transporter 1 and basolateral Na + -coupled neutral amino acid transporter 3 is complemented by glutaminase activity.…”

Section: Survey Methodologymentioning

confidence: 99%

“…The epithelial collecting system also implements NH 3 /NH 4 + transport regulated by a complex process that involves at least two Rhesus glycoproteins: RhB (SLC42A2) and RhC (SLC42A3) ( Harris et al, 2023 ; Takvam et al, 2023 ). Rhbg expressed in IC-α and non-α, non-β intercalated cells, principal cells in the basolateral plasma membrane.…”

Section: Survey Methodologymentioning

confidence: 99%

Mechanisms and physiological relevance of acid-base exchange in functional units of the kidney

Gantsova,

Serova,

Vishnyakova

et al. 2024

PeerJ

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This review discusses the importance of homeostasis with a particular emphasis on the acid-base (AB) balance, a crucial aspect of pH regulation in living systems. Two primary organ systems correct deviations from the standard pH balance: the respiratory system via gas exchange and the kidneys via proton/bicarbonate secretion and reabsorption. Focusing on kidney functions, we describe the complexity of renal architecture and its challenges for experimental research. We address specific roles of different nephron segments (the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule) in pH homeostasis, while explaining the physiological significance of ion exchange processes maintained by the kidneys, particularly the role of bicarbonate ions (HCO3−) as an essential buffer system of the body. The review will be of interest to researchers in the fields of physiology, biochemistry and molecular biology, which builds a strong foundation and critically evaluates existing studies. Our review helps identify the gaps of knowledge by thoroughly understanding the existing literature related to kidney acid-base homeostasis.

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“…Ammonium excretion is particularly important because it can increase considerably under conditions of metabolic acidosis as a compensatory response. 1,2 Disorders of acid-base homeostasis can result in a number of clinical problems such as electrolyte abnormalities, bone disorders, muscle weakness, and cardiac arrhythmias. In humans with progressive chronic kidney disease (CKD), a substantial proportion of individuals (up to 40%) develop metabolic acidosis, where inadequate capacity for ammonia excretion appears to be the driving force.…”

Section: Introductionmentioning

confidence: 99%

“…The 2 normal components of daily acid excretion are titratable acidity and ammonium excretion, which lead to the formation of new bicarbonate. Ammonium excretion is particularly important because it can increase considerably under conditions of metabolic acidosis as a compensatory response 1,2 …”

Section: Introductionmentioning

confidence: 99%

Correlation between urine anion gap and urine ammonia‐creatinine ratio in healthy cats and cats with kidney disease

Berman,

Specht,

Castro

et al. 2024

Veterinary Internal Medicne

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BackgroundAmmonium excretion decreases as kidney function decreases in several species, including cats, and may have predictive or prognostic value in patients with chronic kidney disease (CKD). Urine ammonia measurement is not readily available in clinical practice, and urine anion gap (UAG) has been proposed as a surrogate test.ObjectivesEvaluate the correlation between urine ammonia‐to‐creatinine ratio (UACR) and UAG in healthy cats and those with CKD and determine if a significant difference exists between UAG of healthy cats and cats with CKD.AnimalsUrine samples collected from healthy client‐owned cats (n = 59) and those with stable CKD (n = 17).MethodsUrine electrolyte concentrations were measured using a commercial chemistry analyzer and UAG was calculated as ([sodium] + [potassium]) − [chloride]. Urine ammonia and creatinine concentrations had been measured previously using commercially available enzymatic assays and used to calculate UACR. Spearman's rank correlation coefficient between UAG and UACR was calculated for both groups. The UAG values of healthy cats and cats with CKD were assessed using the Mann‐Whitney test (P < .05).ResultsThe UAG was inversely correlated with UACR in healthy cats (P < .002, r0 = −0.40) but not in cats with CKD (P = .55; r0 = −0.15). A significant difference was found between UAG in healthy cats and those with CKD (P < .001).Conclusions and Clinical ImportanceThe UAG calculation cannot be used as a substitute for UACR in cats. The clinical relevance of UAG differences between healthy cats and those with CKD remains unknown.

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An Update on Kidney Ammonium Transport Along the Nephron

Cited by 10 publications

References 77 publications

Serum Bicarbonate Deficiency in Dogs with Acute and Chronic Kidney Disease

Serum Bicarbonate Deficiency in Dogs with Acute and Chronic Kidney Disease

Mechanisms and physiological relevance of acid-base exchange in functional units of the kidney

Correlation between urine anion gap and urine ammonia‐creatinine ratio in healthy cats and cats with kidney disease

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