Endothelin-induced changes in intracellular calcium in human microglia

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Microglia are key immune cells in the central nervous system.
• Endothelin peptides (ET-1, ET-3) are implicated in various physiological and pathological processes.
• The role of endothelin in human microglia signaling remains incompletely understood.

Purpose of the Study:

• To investigate the effects of endothelin on intracellular calcium levels in cultured human microglia.
• To identify the specific endothelin receptor subtypes involved in mediating these calcium responses.
• To explore the contribution of calcium influx to the observed signaling.

Main Methods:

• Calcium-sensitive spectrofluorometry was employed to measure intracellular calcium ([Ca2+]i).
• Experiments were conducted in both normal and calcium-free solutions.
• Selective endothelin receptor antagonists (ET(A) antagonist BQ610, ET(B) antagonist BQ780) were utilized.

Main Results:

• Both ET-1 and ET-3 induced transient, non-desensitizing increases in [Ca2+]i in over 80% of human microglia.
• Responses were significantly reduced in Ca2+-free solution, indicating substantial calcium influx.
• ET-1-induced responses were unaffected by ET(A) blockade but significantly reduced by ET(B) blockade.

Conclusions:

• Human microglia express functional ET(B) receptors.
• Endothelin signaling in microglia primarily involves ET(B) receptors and relies on extracellular calcium influx.
• These findings suggest a potential signaling pathway between microglia and endothelial cells mediated by ET(B) receptors.