ABSTRACT
Artemetin is one of the main components of Achillea millefolium L. and Artemisia absinthium, which have long been used for the treatment of various diseases. To date, however, available information about protective effects of their extracts on the cardiovascular system is scarce. Therefore, we planned to analyze the effects of artemetin on nitric oxide (NO) release and the protection exerted against oxidation in porcine aortic endothelial (PAE) cells. In PAE, we examined the modulation of NO release caused by artemetin and the involvement of muscarinic receptors, ß2-adrenoreceptors, estrogenic receptors (ER), protein-kinase A, phospholipase-C, endothelial-NO-synthase (eNOS), Akt, extracellular-signal-regulated kinases 1/2 (ERK1/2) and p38 mitogen activated protein kinase (p38 MAPK). Moreover, in cells treated with hydrogen peroxide, the effects of artemetin were examined on cell survival, glutathione (GSH) levels, apoptosis, mitochondrial membrane potential and transition pore opening. Artemetin increased eNOS-dependent NO production by the involvement of muscarinic receptors, ß2-adrenoreceptors, ER and all the aforementioned kinases. Furthermore, artemetin improved cell viability in PAE that were subjected to peroxidation by counteracting GSH depletion and apoptosis and through the modulation of mitochondrial function. In conclusion, artemetin protected endothelial function by acting as antioxidant and antiapoptotic agent and through the activation of ERK1/2 and Akt. Copyright © 2015 John Wiley & Sons, Ltd.
ABSTRACT
BACKGROUND: Levosimendan protects rat liver against peroxidative injuries through mechanisms related to nitric oxide (NO) production and mitochondrial ATP-dependent K (mitoKATP) channels opening. However, whether levosimendan could modulate the cross-talk between apoptosis and autophagy in the liver is still a matter of debate. Thus, the aim of this study was to examine the role of levosimendan as a modulator of the apoptosis/autophagy interplay in liver cells subjected to peroxidation and the related involvement of NO and mitoKATP. METHODS AND FINDINGS: In primary rat hepatocytes that have been subjected to oxidative stress, Western blot was performed to examine endothelial and inducible NO synthase isoforms (eNOS, iNOS) activation, apoptosis/autophagy and survival signalling detection in response to levosimendan. In addition, NO release, cell viability, mitochondrial membrane potential and mitochondrial permeability transition pore opening (MPTP) were examined through specific dyes. Some of those evaluations were also performed in human hepatic stellate cells (HSC). Pre-treatment of hepatocytes with levosimendan dose-dependently counteracted the injuries caused by oxidative stress and reduced NO release by modulating eNOS/iNOS activation. In hepatocytes, while the autophagic inhibition reduced the effects of levosimendan, after the pan-caspases inhibition, cell survival and autophagy in response to levosimendan were increased. Finally, all protective effects were prevented by both mitoKATP channels inhibition and NOS blocking. In HSC, levosimendan was able to modulate the oxidative balance and inhibit autophagy without improving cell viability and apoptosis. CONCLUSIONS: Levosimendan protects hepatocytes against oxidative injuries by autophagic-dependent inhibition of apoptosis and the activation of survival signalling. Such effects would involve mitoKATP channels opening and the modulation of NO release by the different NOS isoforms. In HSC, levosimendan would also play a role in cell activation and possible evolution toward fibrosis. These findings highlight the potential of levosimendan as a therapeutic agent for the treatment or prevention of liver ischemia/reperfusion injuries.