POSTCONDITIONING ON REPERFUSION ARRHYTHMIAS. EFFECT OF NADOLOL AND A SPECIFIC BETA2 BLOCKER

DIEZ ED, LUCERO GA, PONCE ZUMINO AZ,MIATELLO RM.

Buenos Aires

Congreso; XVII MEETING OF THE INTERNATIONAL SOCIETY FOR HEART RESEARCH, LATIN AMERICAN SECTION; 2009

INTERNATIONAL SOCIETY FOR HEART RESEARCH, LATIN AMERICAN SECTION

The term pharmacological postconditioning (PostC) has been used to describe interventions that confer myocardial protection after a period of ischemia and infarction. The absence of treatment with beta blockers has been identified as a risk factor for the incidence of reperfusion arrhythmias (RA). Isolated hearts from Sprague–Dawley rats, perfused according to Langendorff technique, were submitted to 10min of regional ischemia. PostC was evaluated by administration of 10 μM nadolol (non-selective β blocker) (n=9) or the same doses of ICI 118,551 (β2 blocker) (n=10) in the first 3 min of reperfusion versus control (n=11).We analyzed the incidence and severity of RA and its relationship with changes on ECG and action potentials recorded simultaneously. 82% (CI95% 48–95%) of the control group developed sustained RA (more than 3 min), 40% (12–73%) with β2 blocker and only 11% (0–48%) with nadolol (p=0.08 and p=0.0055 vs. control, respectively, by Fisher test). The heart rate decreased from 261±36 to 126±44 beats/min and 255±44 to 125±33 beats/min with β2 blocker and nadolol, respectively (pb0.05 by ANOVA I). The lower incidence of RAwith nadolol could be associated to bradycardia, but since ICI 118,551 has similar effect, further studies will be needed to elucidate other specific action of nadolol (antioxidant?), absent in the β2 blocker.