Hydrodynamic hyperpolarization of endothelial cells.

Area of Science:

• Cardiovascular Science
• Cell Biology
• Biophysics

Background:

• Endothelial cell orientation and morphology are influenced by hemodynamic forces.
• Understanding flow effects at the cellular membrane level is crucial for cardiovascular research.

Purpose of the Study:

• To investigate the impact of hemodynamic shear stress on endothelial cell membrane potential.
• To analyze the dynamic changes in membrane potential upon initiation and cessation of blood flow.

Main Methods:

• Utilized membrane-sensitive fluorescent dyes (merocyanine 540 and bis(1,3-diethylthiobarbiturate)trimethineoxonol).
• Measured fluorescence intensity variations under controlled flow shear stress conditions.
• Employed ionophores (valinomycin) to assess potassium ion (K+) flux and membrane potential changes.

Main Results:

• Observed a time-dependent, reversible decrease in fluorescence intensity upon flow onset, reaching steady state in approximately 1 minute.
• Demonstrated that the amplitude of fluorescence response, reflecting membrane polarization, increases with shear stress up to 120 dynes/cm2.
• Deduced flow-induced hyperpolarization of the endothelial cell membrane based on ionophore effects and potassium equilibrium potential.

Conclusions:

• Hemodynamic shear stress dynamically alters endothelial cell membrane potential.
• Flow-induced hyperpolarization is a key response of endothelial cells to mechanical forces.
• These findings provide insights into the mechanotransduction mechanisms in the cardiovascular system.