The effects of epinephrine on the electrophysiologic properties of human right atrial tissue, obtained at cardiac surgery, were evaluated utilizing standard microelectrode techniques. In studies of electrophysiology, epinephrine had little effect on the resting membrane potential and transmembrane action potentials of normal atrial fibers. Epinephrine enhanced phase-4 depolarization and increased automaticity in normal fibers but hyperpolarized partially depolarized atrial fibers and decreased automaticity. The hyperpolarizing action of epinephrine resulted in a increase in action potential amplitude and dV/dt and enhanced conduction. Active force increased 40-230% in depressed tissues when exposed to epinephrine. Epinephrine-induced hyperpolarization of depressed atrial fibers may have a beneficial effect on atrial arrhythmias and depressed contractility encountered clinically.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine