Intralipid (5mL/kg) provided five minutes before reperfusion delays the opening of mPTP in vivo rat models, making it a potential cardioprotective agent Lou et al. (2014) found that the cardioprotection aspect of Intralipid is initiated by the accumulation of acylcarnitines in the mitochondria and involves inhibition of the electron transport chain, an increase in ROS production during early (3 min) reperfusion, and activation of the reperfusion injury salvage kinase pathway (RISK). The mitochondrial accumulation of acylcarnitines (primarily palmitoyl-carnitine) inhibits the electron transport chain at complex IV, generating protective ROS. The effects of ROS are both “site” and “time” sensitive, meaning that both will ultimately determine whether the ROS are beneficial or detrimental. The generated ROS, which are formed from electrons leaking from the electron transport chain of the mitochondria, first act directly on mPTP to limit opening. ROS then activate signalling pathways that act on the mitochondria to decrease mPTP opening and mediate protection. Activation of the RISK pathway by ROS increases the phosphorylation of other pathways, such as phosphatidylinositol 3-kinase/Akt and extracellular-regulated kinase (ERK) pathways, both of which are found in pools localized at the mitochondria. The Akt and ERK pathways converge to alter glycogen synthase kinase-3 beta (GSK-3β) activity. Specifically, Akt and ERK phosphorylate GSK-3β, inactivating the enzyme, and inhibiting the opening of mPTP. The mechanism by which GSK-3β inhibits the opening of the mPTP is controversial. Nishihara et al. (2007) proposed that it is achieved through interaction of GSK-3β with ANT subunit of mPTP, inhibiting the Cyp-D–ANT interaction, resulting in the inability of the mPTP to open.