In many cells, a rise in cAMP is well known to activate PKA. Additionally, a recent identified protein Epac (Exchange Protein Activated by cAMP) appears to be a new target for cAMP. In cardiac myocytes, Epac was described as a modulator of Ryanodine receptors (RyR) activity mediated by CaMKII resulting in both increase (1) and decrease (2) of Ca2+ release. This study was therefore designed to investigate the functional role of Epac on Excitation-Contraction coupling using L type Ca2+ current (ICa) as a sensor of Ca2+ released from the sarcoplasmic reticulum as previously described (3). Experiments were performed at room temperature on freshly enzymatically isolated Wistar rat ventricular myocytes. The whole-cell configuration of the patch clamp technique was used to record ICa using Na and K free solutions to avoid overlapping currents. ICa was elicited by a test pulse to 0 mV at 0.1 and 1 Hz. Pharmacological Epac activation was achieved by 8- (4-Chlorophenylthio)- 2′- O- methyladenosine- 3′, 5′- cyclic monophosphate, acetoxymethyl ester (8-CPT-AM). Preincubated cells with 10µM 8-CPT-AM were compared to untreated (control) cells (unpaired t test). Cell size and current density were not significantly different between preincubated 8-CPT-AM and control cells (mean ± SEM, 170 ± 12.4 pF vs 160.3 ± 14.4 pF and 8.49 ± 0.79 pA/pF vs 8.82 ± 0.38 pA/pF respectively, n = 21 for each group). The inactivation kinetic reflecting mainly Ca2+ released assessed by the time to reach 37% of peak current (T0.37) was 11 ± 0.95 ms (control) and 11.4 ± 1 ms (treated) (n = 21, p > 0.05). The frequency-dependent facilitation of ICa from 0.1 to 1 Hz was not different between control (Area I4/I1: 1.29 ± 0.03) compared to treated cells (1.21 ±0.04) (n = 21, p > 0.05). Neither voltage dependence nor availability of ICa was affected by 8-CPT-AM. Because CaMKII affects both L type Ca2+ channels and RyR, the RyR blocker ryanodine (10µM), used to discriminate putative antagonist role of Epac on L type Ca2+ channels and RyR, failed to unmask 8-CPT-AM effect on inactivation kinetic (25.2 ± 1.6 ms vs 24.9 ± 1.2 ms, n = 11 (Rya) and 10 (Rya + 8-CPT-AM) respectively, p > 0.05) and frequency-dependent facilitation of ICa (Area I4/I1: 0.87 ± 0.02 vs 0.86 ± 0.02, n = 11 (Rya) and 10 (Rya + 8-CPT-AM) respectively, p > 0.05). Our results suggest that pharmacological activation of Epac by 8-CPT-AM may not be able to modulate neither L type Ca2+ channel nor RyR activities.