Pharmacological Modulation of the Ca2+/cAMP/Adenosine Signaling in Cardiac Cells as a New Cardioprotective Strategy to Reduce Severe Arrhythmias in Myocardial Infarction

Characterized by severe and fatal arrhythmias induced by cardiac ischemia/reperfusion (CIR), acute myocardial infarction (AMI) is the main cause of morbidity and mortality worldwide. To investigate the cardioprotective role of cardiac Ca2+/cAMP/adenosine signaling in AMI, the effects of L-type Ca2+ channels (LTCC) blocker Nifedipine (NIF) and Verapamil (VER), in the absence and presence of A1-adenosine receptors (A1R) blocker (DPCPX), on the incidence of ventricular arrhythmias (VA), atrioventricular block (AVB) and lethality (LET) induced by CIR in rats were evaluated. CIR was induced in adult male Wistar rats (290-320 g) by occlusion of the left anterior descendent coronary artery (10 min) followed by reperfusion (75 min). VA, AVB and LET incidences were evaluated by ECG analysis and compared between control (CIR group) and intravenously treated 5 min before CIR with NIF 1, 10, and 30 mg/kg (NIF+CIR groups) or DPCPX 100 µg/kg plus NIF 10 mg/kg (DPCPX+NIF+CIR group) and VER 1 mg/kg (VER+CIR group) or DPCPX 100 µg/kg plus VER 1 mg/kg (DPCPX+VER+CIR group). Serum levels of cardiac injury biomarkers (TCK and CK-MB) were quantified. In CIR group, VA, AVB and LET incidences were 90, 80 and 70%, respectively. In NIF+CIR group, incidence of VA was reduced to 50, 30 and 30%, AVB to 25, 10 and 20%, and LET to 25, 20 and 20%, and respectively. In DPCPX+NIF+CIR group, these incidences were not different from CIR group. TCK and CK-MB levels were similar in all groups. These results indicate that pharmacological modulation of the Ca2+/cAMP/adenosine signaling in cardiac cells by LTCC blockade and A1R stimulation could be a new strategy cardioprotective for human AMI therapy.