Acute effects of adrenergic agents on post-defibrillation arrest time in a cultured heart model.
Possible drug interactions with electrical defibrillation were examined. We tested the hypothesis that adrenergic agents (epinephrine, norepinephrine, isoproterenol) and a calcium channel blocker (verapamil), when applied acutely, alter the duration of arrest following a defibrillator shock. A secondary hypothesis (based on observations) was that the drugs alter the occurrence of changes to normal rhythms following the shock. Dissociated heart cells from 10-day chicken embryos were cultured to form spherical aggregates and plated in petri dishes. In the experiments, the spheres were paced at 0.75 V/cm above contraction threshold, and a biphasic defibrillator shock was applied for 1 ms at 46 V/cm. The arrest time and occurrence of rhythm changes were recorded. The adrenergic agents shortened the duration of arrest following a defibrillator shock, while the calcium channel blocker lengthened the arrest time. Comparisons with the control proportion of double beats showed no significant change with the adrenergic agents and a decrease with verapamil.
Krauthamer
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Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, 12725 Twinbrook Parkway, Mail stop HFZ-130, Rockville, Maryland 20852, USA. victor.krauthamer@hhs.fda.gov
Smith
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D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D018920:Coculture Techniques; D004554:Electric Countershock; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects* / Q000502:physiology*; D009206:Myocardium / Q000166:cytology*; D013997:Time Factors
D018663:Adrenergic Agents