Abstract 18701: Sildenafil Attenuates Ethanol-Induced Myocardial Dysfunction and Cytotoxicity
Background: Ethanol (EtOH) induces cardiotoxicity by increasing apoptosis, free radical formation and lipid peroxidation. Since sildenafil has potent cardioprotective effects through activation of protein kinase G, we hypothesized that treatment with sildenafil would attenuate cardiotoxicity associated with acute EtOH exposure by reducing apoptosis and preserving function.
Methods and Results: Mice were treated with EtOH (3 g/kg/day, ip) ± sildenafil (0.7 mg/kg, ip) for 3 days. Cardiac function was measured in Langendorff mode. EtOH treatment decreased rate-force product (g·bpm) (270 ± 26, P < 0.01) as compared to control (433 ± 23), which was preserved with sildenafil co-treatment (392 ± 38). EtOH increased myocardial apoptosis (1.42 ± 0.16%; P < 0.001 vs. control 0.05 ± 0.03%), which was attenuated with sildenafil (0.05± 0.05%). Sildenafil increased myocardial PKG activity with (2.6 fold) or without EtOH (4.6 fold). To further understand the mechanism of protection of sildenafil against EtOH cardiotoxicity, primary rat cardiomyocytes were treated with 100 mM EtOH ± 10 μM sildenafil. At 18 h, necrosis (trypan blue staining); mitochondrial membrane potential (mΔΨ, JC-1; aggregates/monomer); and ROS (DCF; F488 AU) were measured.
At 48 h, apoptosis was assessed by TUNEL. EtOH increased necrosis and apoptosis, which were attenuated with sildenafil (Fig 1). EtOH disrupted mΔΨ (EtOH 1.24 ± 0.17, P < 0.001) and increased ROS production (EtOH 156.73 ± 36.91, P < 0.01) compared to control (13.08 ± 1.78 and 28.09 ± 5.75, respectively). Sildenafil preserved mΔΨ (19.29 ± 3.01) and attenuated ROS production (12.38 ± 5.70). Knockdown of PKG with adenoviral shRNA blocked the protective effect of sildenafil whereas overexpression of PKG1α conferred similar protection against EtOH cytotoxicity (Fig 1).
Conclusion: Sildenafil attenuates the EtOH cardiotoxicity through PKG-dependent maintenance of mitochondrial integrity while preserving cardiac function.
- © 2013 by American Heart Association, Inc.