Ceramide is necessary for decreased mitochondrial respiration in myocardial cells following treatment with conditioned medium from CSE-treated lung cells. A: Ceramide levels in H9C2 cardiomyocytes treated with conditioned medium from A549 alveolar type 2 cells following incubation with normal growth medium (Con), Con with myriocin (Myr), cigarette smoke extract (CSE), and CSE with Myr (CSE + Myr) (n = 4). B: Mitochondrial respiration from H9C2 cardiomyocytes following treatment in identical conditions (n = 5). See Methods for more details on respiration protocol. *P <0.05 for CSE vs. Con.