Automatic and triggered impulse initiation in @entity235 subepicardial ventricular muscle cells from border zones of 24-hour transmural @entity1188 . New mechanisms for malignant XXXX ?

@entity235 @entity245 @entity6237 @entity1188 @entity2661 @entity943 @entity121
With standard microelectrode techniques, electrical activity of cells in the epicardial border zones of @entity1188 in the @entity235 heart were studied. Either automaticity or triggered activity (or both) occurred in each of the 12 preparations studied from 24-hour @entity1188 . One 24-hour preparation had continuous activity indistinguishable from low-potential (abnormal) automaticity. This automaticity was not effected by @entity6237 1-5 mg/l. Two other 24-hour @entity121 also were automatic. However, nine preparations from the subepicardium were not automatic during superfusion with standard Tyrode's solution. @entity245 ( @entity245 ) and triggered activity could be induced in all of these preparations by treatment with @entity2661 . The amplitude of these @entity245 was directly related to the stimulus rate of the train of impulses used to elicit them, and their coupling interval was inversely related to this rate of stimulation. Triggered activity occurred from maximal diastolic potentials of -58 to -88 mV in the 24-hour @entity1188 zone preparations. In seven preparations from 72-96-hour @entity1188 zones, the epicardial muscle cells did not show triggered activity after treatment with @entity2661 . In one preparation from a 72-hour @entity1188 , however, 3-5-mV @entity245 occurred. No @entity245 or triggered impulses occurred in subepicardial muscle from normal, noninfarcted hearts. Thus, triggered impulses and low-potential automaticity could contribute to @entity943 occurring in the @entity235 heart 24 hours after coronary ligation.
