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Updated: Aug 10, 2026
20:38
AC Electrokinetic Phenomena Generated by Microelectrode Structures
Published on: July 28, 2008
Serious workings of the funny current
1Laboratory of Molecular Physiology and Neurobiology, Department of Biomolecular Sciences and Biotechnology, University of Milano, via Celoria 26, 20133 Milano, Italy. dario.difrancesco@unimi.it
Progress in Biophysics and Molecular Biology
|June 25, 2005
Summary
The I(f) current, mediated by hyperpolarization-activated, cyclic-nucleotide-gated (HCN) channels, is crucial for heart pacemaker activity. Understanding these channels aids in developing new heart rate-controlling drugs and biological pacemakers.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Pharmacology
Background:
- The I(f) current, identified in 1979, is fundamental to cardiac pacemaker activity and its modulation by neurotransmitters.
- This current is activated by negative voltage and intracellular cAMP, influencing heart rate via beta-receptor and vagal stimulation.
- The discovery of four hyperpolarization-activated, cyclic-nucleotide-gated (HCN) channel isoforms in the late 1990s provided molecular correlates for native f-channels.
Purpose of the Study:
- To elucidate the role of I(f) current and HCN channels in cardiac pacemaker generation and modulation.
- To explore the potential of I(f) channels as therapeutic targets for heart rate control.
- To guide the development of novel pharmacological agents and biological pacemakers.
Main Methods:
- Comparative analysis of native pacemaker channel properties with cloned HCN channel isoforms.
- Investigation of the molecular composition and regional differences of cardiac pacemaker channels.
- Review of pharmacological agents targeting I(f) current for heart rate modulation.
Main Results:
- The I(f) current is essential for generating and modulating cardiac pacemaker activity.
- HCN channels are the molecular basis of native f-channels, with distinct isoforms in different cardiac regions.
- Selective I(f) inhibitors, like ivabradine, demonstrate efficacy in controlling heart rate for conditions such as angina and heart failure.
Conclusions:
- Understanding HCN channel properties is key to developing targeted cardiac drugs, distinguishing them from neuronal channels.
- The I(f) current represents a significant therapeutic target for pharmacologically managing heart rate.
- Future developments include biological pacemakers utilizing cellular sources of pacemaker channels for rhythm disorder therapies.
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