Fluid Shear Stress Effects on Endothelial Cell Cytosolic pH

Area of Science:

• Physiology
• Cell Biology
• Biochemistry

Background:

• Endothelial cells are crucial for vascular function.
• Intracellular pH (pH(i)) regulation is vital for cellular processes.
• Fluid flow generates shear stress on endothelial cells.

Purpose of the Study:

• To investigate the effect of fluid flow and shear stress on endothelial cell intracellular pH.
• To identify the mechanisms involved in shear stress-induced pH changes.
• To explore the role of pH(i) as a potential second messenger in endothelial cells.

Main Methods:

• Exposure of endothelial cells to varying levels of venous and arterial shear stress.
• Measurement of intracellular pH changes using pH indicators.
• Inhibition of the bicarbonate/chloride exchanger using SITS.
• Perfusion with media containing ATP.

Main Results:

• Both venous and arterial shear stresses induced intracellular acidification in a shear-dependent manner.
• Endothelial cells recovered from venous shear stress-induced acidification but not arterial shear stress.
• SITS significantly reduced shear stress-induced acidification, implicating the HCO(3)(-)/Cl(-) exchanger.
• ATP modulated the kinetics of flow-induced acidification.

Conclusions:

• Fluid flow and shear stress directly modulate endothelial cell pH(i).
• The HCO(3)(-)/Cl(-) exchanger plays a key role in shear stress-induced intracellular acidification.
• pH(i) may function as a second messenger in endothelial cells, influencing metabolism in response to flow.