Related Experiment Video
Updated: Jun 27, 2026
06:11
Culturing Primary Rat Inner Medullary Collecting Duct Cells
Published on: June 21, 2013
Interstitial tonicity controls TonEBP expression in the renal medulla
Mee R Sheen1, Jeong-Ah Kim, Sun W Lim
1Department of Medicine, University of Maryland, Baltimore, Maryland 21201,, USA.
Kidney International
|December 5, 2008
Summary
Kidney cells express TonEBP (tonicity-responsive enhancer binding protein) to combat hyperosmolality. Interstitial hypertonicity in the renal medulla stimulates TonEBP expression, crucial for kidney function and urine concentration.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Physiology
Background:
- Hyperosmotic stress in the kidney medulla is managed by the tonicity-responsive enhancer binding protein (TonEBP).
- TonEBP regulates genes essential for cellular protection and urine concentration, including aquaporin-2 and urea transporters.
Purpose of the Study:
- To investigate the impact of renal medullary interstitial hypertonicity on TonEBP expression.
- To elucidate the regulatory mechanisms of TonEBP in response to osmotic challenges.
Main Methods:
- Induction of massive water diuresis in rats to alter medullary tonicity.
- Administration of furosemide to reduce medullary sodium concentration and interstitial tonicity.
- Measurement of TonEBP expression and mRNA abundance in rat renal medulla.
- Analysis of TonEBP target gene expression.
Main Results:
- Water diuresis did not alter medullary sodium concentration or TonEBP expression.
- Furosemide treatment dose-dependently decreased medullary sodium concentration and interstitial tonicity.
- Furosemide administration led to reduced TonEBP expression in the renal medulla, partly due to decreased mRNA levels.
- Expression of TonEBP target genes was also reduced following furosemide treatment.
Conclusions:
- TonEBP expression in the renal medulla is stimulated by interstitial hypertonicity.
- Maintaining medullary tonicity is critical for regulating TonEBP and its downstream targets involved in kidney function.
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...
01:33Hormonal Regulation
The renin-aldosterone system is an endocrine system which guides the renal absorption of water and electrolytes, thus managing blood pressure and osmoregulation. Activation of the system begins in the kidneys with a small cluster of cells adjacent to the afferent and efferent blood vessels of the renal corpuscle. As the nephrons are filtering blood, juxtaglomerular cells monitor blood pressure. If they detect a decrease in pressure, they release the hormone renin into the bloodstream.
01:23Formation of Concentrated Urine
There is a gradient of solutes in the interstitial fluid from the renal cortex through the medulla, known as the medullary osmotic gradient. The juxtamedullary nephrons establish and maintain this gradient using countercurrent mechanisms with loops extending deep into the medulla. These nephrons also use countercurrent mechanisms to regulate urine volume and concentration. The interaction between the descending and ascending limbs of the nephron loop creates an osmotic gradient through...
01:20Physiology of the Genitourinary System III: Urine Concentration and Dilution
The kidneys concentrate or dilute urine to maintain water and electrolyte balance. Nephrons, particularly the loop of Henle, play a crucial role in this process through the countercurrent multiplication system. This system establishes a high osmolarity in the renal medulla, which is essential for water reabsorption. In the loop of Henle’s descending limb, water is reabsorbed into the surrounding medulla due to its permeability to water. In contrast, the ascending limb actively transports...
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...
01:26Regulation of Sodium and Potassium
The regulation of sodium and potassium ion concentrations in the human body is a complex process governed primarily by hormones such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Sodium Regulation
Sodium ions make up approximately 90% of extracellular cations, with a normal blood plasma concentration of 136–148 mEq/L. A decrease in blood volume and pressure triggers the release of renin from granular cells in the juxtaglomerular complex (JGC), primarily in...
Sodium Regulation
Sodium ions make up approximately 90% of extracellular cations, with a normal blood plasma concentration of 136–148 mEq/L. A decrease in blood volume and pressure triggers the release of renin from granular cells in the juxtaglomerular complex (JGC), primarily in...