Single channel currents induced by complement in antibody-coated cell membranes

Area of Science:

• Membrane biophysics
• Immunology
• Skeletal muscle physiology

Background:

• Antibody-coated skeletal muscle is susceptible to complement-mediated damage.
• Complement activation leads to the formation of membrane attack complexes, forming pores or channels.
• Understanding the biophysical properties of these channels is crucial for comprehending immune-mediated muscle injury.

Purpose of the Study:

• To characterize the single-channel conductance and kinetics of complement-induced channels in skeletal muscle membranes.
• To investigate the dynamic structural transitions of these ion channels.

Main Methods:

• Extracellular patch-clamp electrophysiology was employed to record ionic currents.
• Single-channel currents from individual complement-induced channels were analyzed.
• Unit conductance and channel gating kinetics were determined.

Main Results:

• A unit conductance of approximately 90 pS was estimated from single-channel current amplitudes.
• Channel opening and closing kinetics displayed significant variability and complexity.
• Observed rapid flickering between conducting and nonconducting states suggests dynamic structural transitions.

Conclusions:

• Complement-induced channels in skeletal muscle membranes exhibit a conductance of ~90 pS.
• These channels undergo rapid structural transitions, evidenced by complex flickering kinetics.
• The dynamic nature of these channels is a key feature of complement-mediated membrane damage in muscle.