Cardioprotective effect of preconditioning is more efficient than postconditioning in rats submitted to cardiac ischemia and reperfusion

Abstract

Cardioprotective effect of preconditioning is more efficient than postconditioning in rats submitted to cardiac ischemia and reperfusion 1 AbstractPurpose: To investigate the cardioprotective effects of ischemic preconditioning (preIC) and postconditioning (postIC) in animal model of cardiac ischemia/reperfusion. Methods: Adult rats were submitted to protocol of cardiac ischemia/reperfusion (I/R) and randomized into three experimental groups: cardiac I/R (n=33), preCI + cardiac I/R (n=7) and postCI + cardiac I/R (n=8). After this I/R protocol, the incidence of ventricular arrhythmia (VA), atrioventricular block (AVB) and lethality (LET) was evaluated using the electrocardiogram (ECG) analysis. Results: After reestablishment of coronary blood flow, we observed variations of the ECG trace with increased incidence of ventricular arrhythmia (VA) (85%), atrioventricular block (AVB) (79%), and increase of lethality (70%) in cardiac I/R group. The comparison between I/R + preIC group with I/R group demonstrated significant reduction in VA incidence to 28%, AVB to 0% and lethality to 14%. The comparison of I/R + postIC group with I/R group was observed significance reduction in AVB incidence to 25% and lethality to 25%. Conclusion:The preconditioning strategies produce cardioprotection more efficient that postconditioning against myocardial dysfunctions and lethality by cardiac ischemia and reperfusion.

Cardioprotective effects of pharmacological blockade of the mitochondrial calcium uniporter on myocardial ischemia-reperfusion injury

“…ECG was monitored and recorded from the beginning of the stabilization period with a commercial acquisition system (AqDados 7.02; Lynx Tecnologia Ltda., Brazil) as reported earlier [9][10][11][12][13] . To assess heart rate, incidences of reperfusion-induced ventricular arrythmia (VA), atrioventricular block (AVB) and lethality (LET), raw data were analyzed with a commercial software package included in the acquisition system (AqDAnalysis 7, Lynx Tecnologia Ltda.).…”

Pharmacological modulation of b-adrenoceptors as a new cardioprotective strategy for therapy of myocardial dysfunction induced by ischemia and reperfusion

“…This sympathetic hyperactivity is also involved in other cardiovascular dysfunctions, including the acute myocardial infarction (AMI). However, a growing number of evidences suggest that the sympathetic hyperactivity associated to cardiovascular diseases could stimulate the cardioprotective response 8 - 11 , 29 . However, the molecular mechanisms involved in this cardioprotective response remains unclear.…”

“…The method for induction of CIR has previously been described by our lab 11 , 13 - 15 . Rats were anesthetized with urethane (1.25 g/kg), and fixed in the supine position.…”

“…After of 10 min of cardiac ischemia, the tourniquet was removed to allow coronary recirculation for 75 min (cardiac reperfusion). The cardiac electrical activity in all groups studied was monitored by electrocardiogram (ECG) system using a method previously described by our lab 11 , 13 - 15 . ECG analysis was performed during 100 min of duration (stabilization for 15 min, cardiac ischemia for 10 min and cardiac reperfusion for 75 min).…”

“…Following this line of reasoning, in vitro and in vivo studies using animal models of CIR showed that treatment with β-adrenoceptor (β-AR) agonist isoproterenol (ISO) or ischemic preconditioning (IPC) protocol reduced infarct size, cardiac necrosis and ventricular arrhythmia (VA), reinforcing the concept of sympathetic mechanisms involvement in cardioprotection 8 - 11 . In this sense, to investigate the role of β-AR in cardioprotection, we studied the effects of agonists and antagonist of β-AR on the cardiac arrhythmias, lethality (LET) and serum levels of cardiac injury markers in spontaneously hypertensive (SHR) and normotensive (NWR) rats submitted to CIR.…”