Abstract
The induction of automaticity by catecholamines in isolated driven cat atrial appendages was investigated. Isolated appendages do not beat spontaneously after separation from the atria. Rhythmic beating in appendages was induced in the presence of an electrical stimulus and catecholamine, but not with either one alone. Isoproterenol was 6 times more potent than epinephrine and norepinephrine in inducing automaticity.
DCI blocked the induction of automaticity by epinephrine and norepinephrine. An autoinhibitory action of isoproterenol on induced automaticity also was revealed. Isoproterenol, like DCI, blocked the induction of automaticity by epinephrine and norepinephrine. The possibility that DCI and isoproterenol block induced automaticity by the same mechanism is discussed.
Footnotes
- Received May 27, 1963.
- Accepted July 31, 1963.
- The Williams & Wilkins Company
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