The hypothetical role of potassium conductance on the genesis of R-wave amplitude increase during ischemia in the isolated rat heart

N. Ferrara, P. Abete, D. Leosco, P. Caccese, S. Sederino, P. Landino, L. De Caprio, D. Acanfora, F. Rengo

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of increased potassium conductance on the genesis of R-wave amplitude increase during acute myocardial ischemia has been studied in the isolated perfused rat heart by simultaneously recording the R-wave amplitude of epicardial electrograms (VEE), heart rate (HR), coronary flow rate (CFR), left ventricular diastolic pressure (LVDP), and left ventricular systolic pressure (LVSP). The experiments were performed during basal and partial or total ischemic conditions at spontaneous or fixed HR. In some experiments, potassium conductance was increased by means of high-calcium (8 mM) or acetylcholine chloride (10-6 M) perfusion. In the control experiments, partial ischemic perfusion produced an increase in VEE and LVDP and a decrease in HR, CFR, and LVSP; total ischemic perfusion exaggerated these variations. High-calcium perfusion provoked an increase in VEE and LVDP and a decrease in HR, CFR, and LVSP during basal conditions (p <0.01 vs. control experiment); these modifications increased progressively during partial ischemic perfusion (p <0.01 vs. control experiment) and during total ischemic perfusion (p <0.01 vs. control experiment). Perfusion with acetylcholine chloride produced variations similar to those observed in high-calcium solution except that LVDP under basal conditions remained unchanged from control. When the HR was maintained at a constant value by means of atrial pacing the results were similar to those observed in the unpaced hearts. In conclusion, in the isolated perfused rat heart, increasing potassium conductance may influence the genesis of R-wave amplitude increasing during acute myocardial ischemia.

Original languageEnglish
Pages (from-to)994-1000
Number of pages7
JournalCanadian Journal of Physiology and Pharmacology
Volume69
Issue number7
Publication statusPublished - 1991

Keywords

  • Acetylcholine
  • Acute myocardial ischemia
  • High calcium
  • Potassium conductance
  • R-wave

ASJC Scopus subject areas

  • Physiology
  • Pharmacology

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