Functional connexin "hemichannels": a critical appraisal

Area of Science:

• Cell Biology
• Molecular Physiology
• Biophysics

Background:

• Hemichannels are defined as single-cell contributions to gap junction channels (connexons).
• Functional hemichannels are open in nonjunctional membranes independently of adjacent cell pairing.
• Existing reviews often assume connexons form the permeability pathway in studies of hemichannels.

Purpose of the Study:

• To critically evaluate the concept and properties of functional hemichannels.
• To assess the evidence for attributed hemichannel functions.
• To propose criteria for verifying connexin hemichannel involvement in cellular and tissue functions.

Main Methods:

• Literature review and conceptual analysis.
• Comparison of presumptive hemichannel properties with theoretical expectations.
• Evaluation of alternative channel types potentially fulfilling similar roles.

Main Results:

• The study of hemichannels is technically demanding and prone to misinterpretation.
• Rigorous standards are essential for detecting hemichannel expression and function.
• Established techniques for studying gap junctions may not be suitable for hemichannel detection.

Conclusions:

• Future research requires stringent criteria to confirm hemichannel activity.
• Researchers should approach hemichannel studies with caution and an open mind.
• Potential for unexpected findings exists, challenging current methodologies.