Chronic Alcohol Consumption Induces Cardiac Nitrosative Stress and Cell Death in an Ang II‐, PKC‐, and NOX‐Dependent Manner

Abstract

Mechanism for alcoholic cardiomyopathy (ACM) remains largely unclear. To this end, male C57BL/6 mice were pair-fed an alcohol or isocaloric control diet for 2 months. Hearts from alcohol-fed mice exhibited increased apoptosis and nitrosative stress. Direct exposure of cardiac H9c2 cells to alcohol induced apoptosis, nitrosative stress and NADPH oxidase (NOX) activation in a dose-dependent manner. Pre-incubation with urate (peroxynitrite scavenger), L-NAME (NO synthase inhibitor), MnTMPyP (SOD mimic) and apocynin (NOX inhibitor) abrogated alcohol-induced apoptosis and nitrosative stress. Furthermore, exposure to alcohol significantly increased the expression of angiotensin II (Ang II) and its type 1 receptor (AT1). A PKCα/β1 inhibitor or an AT1 blocker prevented alcohol-induced NOX activation, and an AT1 blocker inhibited the expression of PKCβ1, indicating that alcoholic NOX activation is dependent on PKCα/β1 activation via AT1. To define the role of NOX derived superoxide in ACM, mice were treated with alcohol and MnTMPyP for 2 months. MnTMPyP prevented cardiac nitrosative stress, cell death, fibrosis and dysfunction, but had no effects on alcoholic hypertension. Our results suggest that alcoholic cardiac apoptosis and nitrosative stress is mediated by Ang II/AT1 interaction and subsequent activation of a PKCα/β1-dependent NOX pathway, which plays a critical role in the development of ACM.