Tissue-specific mitochondrial toxicity of cigarette smoke concentrate: consequence to oxidative phosphorylation.

Cigarette smoke exposure is a well-known risk factor for developing numerous chronic health conditions, including pulmonary disease and cardiometabolic disorders. However, the cellular mechanisms mediating the toxicity of cigarette smoke in extra-pulmonary tissues are still poorly understood. Therefore, the purpose of this study was to characterize the acute dose-dependent toxicity of cigarette smoke on mitochondrial metabolism by determining the susceptibility and sensitivity of mitochondrial respiration from murine skeletal (gastrocnemius and soleus) and cardiac muscles, as well as the aorta to cigarette smoke concentrate (CSC). In all tissues, exposure to CSC inhibited tissue-specific respiration capacity, measured by high-resolution respirometry, according to a biphasic pattern. With a breakpoint of 451±235 μg/mL, the aorta was the least susceptible to CSC-induced mitochondrial respiration inhibition compared to the gastrocnemius (151±109 μg/mL; p=0.008, d =2.3), soleus (211±107 μg/mL; p=0.112; d =1.7), and heart (94±51 μg/mL; p<0.001; d =2.6) suggesting an intrinsic resistance of the vascular smooth muscle mitochondria to cigarette smoke toxicity. In contrast, the cardiac muscle was the most susceptible and sensitive to the effects of CSC, demonstrating the greatest decline in tissue-specific respiration with increasing CSC concentration (p<0.001, except the soleus). However, when normalized to citrate synthase activity to account for differences in mitochondrial content, cardiac fibers' sensitivity to cigarette smoke inhibition was no longer significantly different from both fast-twitch gastrocnemius and slow-twitch soleus muscle fibers, thus suggesting similar mitochondrial phenotypes. Collectively, these findings established the acute dose-dependent toxicity of cigarette smoke on oxidative phosphorylation in permeabilized tissues involved in the development of smoke-related cardiometabolic diseases.