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Changes in autorhythmic heart frequency elicited by redox agents
1Central Laboratory of Animal Research, University Medical School, Pécs, Hungary.
Chemico-Biological Interactions
|January 1, 1987
Summary
Oxidizing agents like methylene-blue (MB) and reducing agents such as ascorbate (ASC) affect heart rate by altering extracellular potassium levels. These redox agents may modulate heart rhythm by influencing potassium channels and active transport systems.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
Background:
- Autorhythmic heart contractions are crucial for cardiac function.
- Extracellular potassium concentration ([K+]o) influences heart rate.
- Redox agents can modulate cellular processes.
Purpose of the Study:
- To investigate the effects of oxidizing and reducing agents on frog heart contraction frequency.
- To explore the role of extracellular potassium ([K+]o) in mediating these effects.
- To elucidate the mechanisms by which redox agents modulate cardiac pacemaking.
Main Methods:
- Isolated frog heart preparations.
- Treatment with methylene-blue (MB) as an oxidizing agent.
- Treatment with ascorbate (ASC) as a reducing agent.
- Measurement of extracellular potassium concentration ([K+]o).
Main Results:
- Methylene-blue (MB) decreased heart contraction frequency and increased [K+]o.
- Ascorbate (ASC) increased heart contraction frequency and decreased [K+]o.
- Insulin (INS) and K-strophantoside (STR) affected these modulatory influences, suggesting involvement of active transport.
- Changes in passive K+ fluxes indicate an effect on K+-channels.
Conclusions:
- Redox agents modulate heart rate through changes in [K+]o.
- These effects may involve alterations in active transport systems and K+-channel characteristics.
- Extracellular potassium dynamics are a key mechanism in redox agent-mediated heart rate modulation.