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Structure-activity relations of the cardiac gap junction channel
1Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461.
The American Journal of Physiology
|February 1, 1990
Summary
Cardiac gap junction channels synchronize heart cells. Various substances alter their function by affecting channel gating, offering potential therapeutic targets for heart rhythm disorders.
Area of Science:
- Cardiovascular Physiology
- Molecular Biology
- Pharmacology
Background:
- Cardiac gap junction channels are crucial for synchronized electrical activity in the heart.
- These channels facilitate ion and small molecule passage between cells, influencing impulse propagation.
Purpose of the Study:
- To investigate the effects of various chemical agents on cardiac gap junction channel function.
- To identify potential pharmacological targets for modulating cardiac electrical activity.
Main Methods:
- Studied unitary conductance and gating properties of cardiac gap junction channels.
- Examined the influence of pH, calcium ions, lipophilic molecules, and cyclic nucleotides.
- Cloned and sequenced the rat heart gap junction protein.
Main Results:
- Cytoplasmic acidification and elevated calcium reduce junctional conductance.
- Lipophilic molecules and arachidonic acid decrease conductance, potentially by disrupting the channel microenvironment.
- Cyclic nucleotides (cAMP, cGMP) and protein kinase C activators modulate conductance.
- Gating stimuli that close channels do not alter unitary conductance, indicating a change in open probability.
Conclusions:
- Cardiac gap junction channels are regulated by diverse stimuli, including pH, ions, and pharmacological agents.
- Understanding these regulatory mechanisms provides a basis for developing therapeutics to control cardiac rhythm and conduction.