Figure 4.

Proposed mechanisms for the production of ROS in various cells types. Nicotine causes epithelial cell damage that results in the production of ROS. Nicotine also triggers the production of ROS by the up-regulation of NADPH in macrophages. Nicotine causes increases in lipid peroxides and decreased GSH in fatty liver disease. Nicotine also triggers the production of ROS through injury and up-regulation of NADPH and NOX4 in mesangial cells. Nicotine is implicated in ROS generation in other cell types and future research directions. Overlap of these mechanisms (not shown) likely occurs. Some of these mechanisms (i.e., decreased GSH) are suspected in many systems.