A method for assessing ionic and molecular permeation in connexin hemichannels.

Area of Science:

• Cellular Biology
• Biophysics
• Molecular Physiology

Background:

• Connexin hemichannels facilitate transport of ions and molecules, crucial for cellular functions.
• Existing methods for assessing hemichannel permeability have limitations in simultaneously evaluating ionic and molecular transport under varied gating stimuli.
• Current techniques struggle with quantitative analysis and simultaneous assessment of permeability to diverse molecules.

Purpose of the Study:

• To introduce a novel methodology for simultaneous evaluation of ionic and molecular permeability through connexin hemichannels.
• To overcome the technical and quantitative limitations of existing assays for studying hemichannel transport.
• To provide a detailed protocol for a combined electrophysiology and dye uptake assay.

Main Methods:

• Development of a novel assay combining two-electrode voltage clamp (TEVC) and dye uptake in Xenopus oocytes.
• Utilizing TEVC to control channel gating with stimuli like voltage or extracellular calcium.
• Employing dye uptake assays to monitor molecular transport kinetics concurrently with electrical measurements.

Main Results:

• The novel TEVC/Dye uptake assay enables simultaneous measurement of ionic and molecular permeability.
• This method allows for kinetic evaluation of molecular transport through connexin hemichannels.
• The protocol is detailed step-by-step for practical application.

Conclusions:

• The developed TEVC/Dye uptake assay offers a significant advancement for studying connexin hemichannel function.
• This methodology can be extended to assess other large pore channels, including pannexin and CALHM channels.
• The assay provides a robust platform for understanding channel selectivity and permeability under physiological conditions.