Effects of diltiazem on triggered activity in canine 1 day old infarction.
Triggered activity arising from a delayed after-depolarisation occurs in canine subendocardial Purkinje fibres 1 day following infarction. Standard microelectrode techniques were used to study small preparations (less than 50 mm2) in vitro. Diltiazem, 1 mg X litre-1, reversibly suppressed triggered activity by reducing maximum diastolic potential, action potential amplitude and the rate of depolarisation of the delayed after-depolarisation. Complete quiescence or exit block resulted. The effects of diltiazem were antagonised by elevating extracellular Ca ion concentration. These results suggest that automatic ectopic rhythms 1 day following myocardial infarction, that are the result of triggered activity, are dependent on transmembrane Ca ion movement which diltiazem can directly antagonise.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D004110:Diltiazem / Q000494:pharmacology*; D004285:Dogs; D004558:Electric Stimulation; D006329:Heart Conduction System / Q000187:drug effects*; D009203:Myocardial Infarction / Q000503:physiopathology*; D011690:Purkinje Fibers / Q000166:cytology / Q000187:drug effects* / Q000503:physiopathology; D013997:Time Factors
D001552:Benzazepines; D004110:Diltiazem; D002118:Calcium