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Pacemaker activity is modulated by tissue levels of cyclic adenosine 3′,5′-monophosphate in human atrial fibers

Authors
Journal
International Journal of Cardiology
0167-5273
Publisher
Elsevier
Publication Date
Volume
25
Issue
1
Identifiers
DOI: 10.1016/0167-5273(89)90160-5
Keywords
  • Cardiovascular Research
Disciplines
  • Medicine

Abstract

Abstract We studied the role of tissue cyclic AMP levels in the chronotropic effects of theophylline on automatic human atrial fibers obtained from the hearts of 17 patients undergoing corrective open-heart surgery. Atrial fibers were perfused with Tyrode solution and transmembrane action potentials were recorded with a conventional microelectrode technique. In normal Tyrode solution, theophylline (0.1–1 mM) often decreased the late diastolic slope and the spontaneous rate. In the presence of 0.3–1 μM epinephrine, however, theophylline dose-dependently increased the diastolic slope, the rate of spontaneous discharges and the force of contraction. The increase in tissue level of cyclic AMP (+288 ± 69%) induced by 0.3 mM theophylline in the presence of epinephrine was much greater than the increase (+73 ± 19%) in the absence of epinephrine. It is concluded that pacemaker activity in human atrial fibers is modulated by tissue levels of cyclic AMP and theophylline may induce atrial tachycardia through an increase in the diastolic slope and the rate of discharges of automatic atrial fibers.

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