FIG. 8.
RyR activity is enhanced, and SERCA pump activity is decreased by ROS/RNS. ROS/RNS enhance the RyR activity directly or by inhibiting the interaction with triadin (TRI) that alters the Ca+2 sensitivity of receptor in the SR. Triadin stabilizes binding of calsequestrin (CSQ) to the RyR. ROS also decrease the ability of RyR to bind with calmodulin (CAM), thereby decreasing the activity. ROS decrease the activity of SERCA by direct interaction or by decreasing the cellular ATP content necessary for the SERCA activity. XO, xanthine oxidase; HyXa, hypoxanthine; Xa, xanthine.