The membrane potential modulates thrombin-stimulated Ca²⁺ mobilization and platelet aggregation

Area of Science:

• Cellular Electrophysiology
• Platelet Biology
• G Protein-Coupled Receptor Signaling

Background:

• G protein-coupled receptors (GPCRs) can be modulated by transmembrane voltage.
• The role of membrane potential in platelet activation and calcium signaling is not fully understood.

Purpose of the Study:

• To investigate the direct modulation of G protein-coupled receptors (PAR-1 and PAR-4) by membrane voltage in human platelets.
• To elucidate the voltage-dependent mechanisms underlying calcium release and platelet aggregation.

Main Methods:

• Patch-clamp electrophysiology to measure membrane potential.
• Fluorescent calcium imaging to monitor intracellular calcium concentrations.
• Platelet aggregation assays.
• Pharmacological activation of GPCRs and downstream signaling pathways.

Main Results:

• Membrane depolarization affects thrombin- or agonist-induced calcium release from intracellular stores.
• Direct G protein or phospholipase C activation bypasses voltage sensitivity.
• Calcium influx and plasma membrane Ca(2+)-ATPase activity are modulated by membrane voltage.
• Platelet aggregation is partially independent of calcium and modulated by membrane depolarization.

Conclusions:

• PAR-1 and PAR-4 receptors in human platelets are modulated by transmembrane voltage.
• Voltage-sensitive regulatory mechanisms influence calcium signaling and platelet aggregation.
• Membrane potential plays a significant role in fine-tuning platelet responses.