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Ionic currents and action potentials in rabbit, rat, and guinea pig ventricular myocytes
A Varró1, D A Lathrop, S B Hester
1Department of Pharmacology, Szent-Györgyi Albert Medical University, Szeged, Hungary.
Basic Research in Cardiology
|March 1, 1993
Summary
Ventricular myocytes from rabbits, rats, and guinea pigs show distinct action potentials and ionic currents. These differences in ion channel activity explain the observed variations in cardiac action potential shapes across species.
Area of Science:
- Cardiology
- Electrophysiology
- Comparative Physiology
Background:
- Cardiac action potentials and ionic currents are crucial for heart function.
- Interspecies variations in myocyte electrophysiology can impact cardiac behavior.
Purpose of the Study:
- To investigate and compare action potentials and ionic currents in ventricular myocytes from rabbits, rats, and guinea pigs.
- To elucidate the ionic basis for observed differences in action potential configurations.
Main Methods:
- Electrophysiological recordings (action potentials, ionic currents) were performed on isolated ventricular myocytes.
- Experiments were conducted at room temperature.
- Ionic currents analyzed included transient outward, inward calcium, inward rectifier potassium, and delayed rectifier outward currents.
Main Results:
- Rabbit myocytes showed prominent phase 1 repolarization and transient outward current in about half of cells.
- Rat ventricular action potentials were shorter, with prominent phase 1 and a lacking plateau phase; all exhibited transient outward current.
- Inward calcium currents were similar across species; inward rectifier potassium current was reduced in rats; delayed rectifier outward current was prominent in guinea pigs but negligible in rabbits and rats.
Conclusions:
- Significant interspecies differences exist in ventricular myocyte action potentials and outward membrane currents.
- These variations in ionic currents, particularly outward currents, underlie the distinct action potential configurations observed in rabbit, rat, and guinea pig ventricular myocytes.