title: The hypothetical role of potassium conductance on the genesis of R-wave amplitude increase during ischemia in the isolated rat heart.
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 less than 0.01 vs. control experiment); these modifications increased progressively during partial ischemic perfusion (p less than 0.01 vs. control experiment) and during total ischemic perfusion (p less than 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.
authors.affiliation: Istituto di Medicina Interna, Cardiologia e Chirurgia Cardiovascolare, II Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Ferrara
authors.forename: P
authors.initials: P
authors.lastname: Abete
authors.forename: D
authors.initials: D
authors.lastname: Leosco
authors.forename: P
authors.initials: P
authors.lastname: Caccese
authors.forename: S
authors.initials: S
authors.lastname: Sederino
authors.forename: P
authors.initials: P
authors.lastname: Landino
authors.forename: L
authors.initials: L
authors.lastname: De Caprio
authors.forename: D
authors.initials: D
authors.lastname: Acanfora
authors.forename: F
authors.initials: F
authors.lastname: Rengo
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D003326:Coronary Circulation / Q000502:physiology; D003327:Coronary Disease / Q000503:physiopathology*; D004562:Electrocardiography; D066298:In Vitro Techniques; D008297:Male; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D015220:Calcium Channels; D015221:Potassium Channels; D000109:Acetylcholine; D002118:Calcium