Regulation of gap junctional conductance

Area of Science:

• Cellular Biology
• Physiology
• Biophysics

Background:

• Gap junctional conductance is a key regulator of intercellular communication.
• This conductance depends on the number of functional channels and their open state (gating).
• Understanding these regulatory mechanisms is vital for normal cardiac function and understanding conduction disorders.

Purpose of the Study:

• To review the regulatory mechanisms of gap junctional conductance.
• To explore factors influencing gap junction formation and removal.
• To discuss the gating mechanisms and modulators of gap junctional conductance, including pH and calcium.

Main Methods:

• Literature review of studies on gap junction regulation.
• Analysis of factors affecting channel formation and degradation.
• Examination of gating mechanisms, including voltage dependence, pH, and intracellular calcium.

Main Results:

• Gap junction formation can be influenced by adenosine 3',5'-cyclic monophosphate (cAMP) and requires protein synthesis.
• Junction removal occurs via particle dispersion and membrane internalization; factors promoting this are less understood.
• Cytoplasmic acidification and increased intracellular calcium decrease gap junctional conductance, with H+ being a more potent modulator than Ca2+ in many cases.
• Higher alcohols like octanol and antibodies to gap junctions can block conductance, indicating conserved structural elements.

Conclusions:

• Gap junctional conductance is modulated by both the quantity and gating of channels.
• While specific factors influencing channel removal require further investigation, pH and Ca2+ play significant roles in conductance regulation.
• The conserved nature of gap junctions suggests a general physiology relevant to cardiac function and disease.