Ammonium transport in the kidney
Dominique Eladari1, Régine Chambrey
1UPMC University of Paris 06; and INSERM UMRS 872 Team 3; CNRS ERL7226, Laboratory of Renal Genomics, Physiology and Physiopathology, Centre de recherche des Cordeliers, Paris, France. dominique.eladari@crc.jussieu.fr
Journal of Nephrology
|December 21, 2010
Summary
The kidney excretes acid mainly via ammonium. New research highlights the roles of Na+/H+ exchanger NHE4 and the Rhcg gas channel in ammonium reabsorption and transport along the nephron.
Area of Science:
- Nephrology
- Renal Physiology
- Acid-Base Balance
Background:
- Renal acid excretion is primarily mediated by ammonium excretion.
- Ammonium is produced in proximal tubule cells and secreted into the tubular fluid.
- Ammonium reabsorption in the thick ascending limb (TAL) is crucial for creating an interstitial gradient necessary for final ammonia excretion.
Purpose of the Study:
- To review the mechanisms of ammonium transport along the nephron.
- To emphasize the roles of newly identified molecules in renal ammonium handling.
- To update on recent findings regarding renal acidosis and ammonium excretion.
Main Methods:
- Review of recent evidence from mouse models of renal acidosis.
- Analysis of the function of specific molecular transporters and channels involved in ammonium transport.
- Examination of the physiological processes of ammonium reabsorption and ammonia diffusion.
Main Results:
- The Na+/H+ exchanger NHE4 is identified as critical for ammonium absorption in the TAL.
- The gas channel Rhcg is essential for ammonia (NH3) diffusion across collecting duct cell membranes.
- These molecular players are key to establishing the corticopapillary ammonium gradient.
Conclusions:
- NHE4 and Rhcg represent significant advancements in understanding renal ammonium transport.
- These findings provide new insights into the molecular mechanisms of acid-base homeostasis.
- Further research into these pathways could inform therapeutic strategies for renal acidosis.
More Related Videos
06:32Evaluation of Amino Acid Consumption in Cultured Bone Cells and Isolated Bone Shafts
Published on: April 13, 2022
12:48Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays
Published on: February 19, 2013
Related Concept Videos
01:22Physiology of the Genitourinary System II: Tubular Reabsorption and Secretion
The kidneys maintain homeostasis through filtration, reabsorption, and secretion. Tubular reabsorption and secretion are crucial in forming urine and regulating electrolytes, water balance, and waste elimination.Tubular Reabsorption and Secretion ProcessesTubular reabsorption is the process that reclaims essential substances such as electrolytes, glucose, amino acids, and water from the glomerular filtrate back into the bloodstream. This is achieved through passive and active transport...
01:28Reabsorption and Secretion in the PCT
The Proximal Convoluted Tubule, or PCT, plays a pivotal role in the body's filtration system. They are primarily responsible for reabsorbing solutes and water from the filtered fluid produced by the glomeruli. Most of the filtered water, ions, and organic solutes such as glucose and amino acids are reabsorbed by the PCT.
Transport mechanisms involving sodium ions (Na+) contribute significantly to solute reabsorption. These mechanisms include symport and antiport processes.
A key example is the...
Transport mechanisms involving sodium ions (Na+) contribute significantly to solute reabsorption. These mechanisms include symport and antiport processes.
A key example is the...
01:15Drug Elimination by Renal Route: Tubular Secretion
Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...
01:17Reabsorption and Secretion in the Loop of Henle
The thick ascending limb of the nephron loop has Na+–K+–2Cl− symporters in the apical membranes of its cells. These symporters simultaneously reclaim one sodium ion, one potassium ion, and two chloride ions from the tubular fluid. Sodium ions are actively transported into the interstitial fluid at the base and sides of the cell, diffusing into the vasa recta. Chloride ions move through leakage channels in the basolateral membrane into the interstitial fluid and then into the vasa recta.
01:28Tubular Reabsorption and Secretion
Tubular secretion and reabsorption are two critical processes in the nephron tubule of the kidneys. When the fluid filtered from the glomerulus enters the proximal convoluted tubule, it is referred to as filtrate, and its composition changes due to tubular reabsorption and secretion.
Tubular reabsorption is a selective process that starts when the filtrate enters the proximal tubules. It involves substances traveling through the transcellular route (through the tubule cell and peritubular...
Tubular reabsorption is a selective process that starts when the filtrate enters the proximal tubules. It involves substances traveling through the transcellular route (through the tubule cell and peritubular...
01:29Renal Regulation of Acid-Base Balance
Metabolic reactions in the body produce nonvolatile acids, such as sulfuric acid, which generate an acid load of approximately 1 mEq of H+ per kilogram of body weight daily. Excreting H+ in the urine is essential to balance this acid load.
In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.
However, the intercalated cells in...
In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.
However, the intercalated cells in...