Related Experiment Video
Updated: Jul 8, 2026
07:42
Live Cell Imaging during Mechanical Stretch
Published on: August 19, 2015
Cellular stretch increases superoxide production in the thick ascending limb
Jeffrey L Garvin1, Nancy J Hong
1Hypertension and Vascular Research Division, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI 48202, USA. jgarvin1@hfhs.org
Hypertension (Dallas, Tex. : 1979)
|December 26, 2007
Summary
Mechanical stretch, not pressure or shear stress, stimulates superoxide production in kidney tubules. This finding in the thick ascending limb (TAL) may explain kidney damage in conditions like hypertension and diabetes.
Area of Science:
- Nephrology
- Physiology
- Biochemistry
Background:
- Superoxide (O(2)(-)) plays a key role in regulating kidney function.
- Previous research indicated that luminal flow stimulates O(2)(-) production in the thick ascending limb (TAL).
- Mechanical factors like stretch, pressure, and shear stress are altered by changes in TAL flow.
Purpose of the Study:
- To investigate whether tubular stretch, pressure, or shear stress is the primary stimulus for flow-induced superoxide production in the TAL.
- To differentiate the roles of mechanical forces in regulating O(2)(-) production in the kidney.
Main Methods:
- Isolated perfused rat TALs were used to measure O(2)(-) production via fluorescence microscopy and dihydroethidium.
- Tubules were perfused with a Na-free solution to isolate mechanical effects from Na transport.
- Experimental conditions manipulated flow, pressure, and stretch independently to assess their impact on O(2)(-) production.
Main Results:
- Increased luminal flow significantly elevated O(2)(-) production in TALs (from 29+/-4 to 90+/-8 AU/s).
- Increasing tubular stretch, independent of shear stress, significantly increased O(2)(-) production (from 40+/-6 to 118+/-17 AU/s).
- Shear stress alone did not affect O(2)(-) production, and stretch was identified as the main contributor to flow-induced O(2)(-) production, inhibited by Tempol.
Conclusions:
- Tubular stretch, rather than pressure or shear stress, accounts for the mechanical stimulation of superoxide production in the TAL.
- Increased TAL stretch during hypertension, diabetes, or salt loading may contribute to renal damage.
- Understanding these mechanisms is crucial for developing strategies to protect kidney function.
Related Concept Videos
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
01:26Cellular Adaptation II: Hypertrophy
Hypertrophy is the increase in the size of individual cells, resulting in the enlargement of a tissue or organ. Unlike hyperplasia, which involves an increase in cell number, hypertrophy is characterized by an increase in cell volume. This process often occurs in response to higher functional demand or hormonal stimulation, leading to the production of more structural proteins and organelles, thereby enhancing the cells' work capacity.There are two primary types of hypertrophy: physiological...
01:00Cellular Injury I: Introduction
Cellular injury occurs when a cell cannot maintain homeostasis or adapt to stressors such as hypoxia, toxins, or trauma. Depending on severity and duration, injury may be reversible, allowing recovery, or irreversible, leading to cell death.General Mechanisms of Cell InjuryAlthough causes vary, most cellular injuries arise from a few key mechanisms that disrupt essential functions and often amplify one another. Cell survival depends on the extent and balance of these disturbances.ATP depletion...
01:21Paracrine Signaling
Paracrine signaling allows cells to communicate with their immediate neighbors via secretion of signaling molecules. Such a signal can only trigger a response in nearby target cells because the signal molecules degrade quickly or are inactivated if not taken up. Prominent examples of paracrine signaling include nitric oxide signaling in blood vessels, synaptic signaling of neurons, the blood clotting system, tissue repair/wound healing, and local allergic skin reactions. Nitric oxide as a...
01:41The Supercomplexes in the Crista Membrane
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
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.