[Protective effect and mechanism of Astragalus membranaceus and Angelica sinensis compatibility against triptolide-induced hepatotoxicity by regulating Keap1/Nrf2/PGC-1α].

This paper aims to investigate the protective effect and mechanism of Astragalus membranaceus and Angelica sinensis before and after compatibility against triptolide(TP)-induced hepatotoxicity. The experiment was divided into a blank group, model group, Astragalus membranaceus group, Angelica sinensis group, and compatibility groups with Astragalus membranaceus/Angelica sinensis ratio of 1∶1, 2∶1, and 5∶1. TP-induced hepatotoxicity model was established, and corresponding drug intervention was carried out. The levels of alanine transaminase(ALT), aspartate transaminase(AST), and alkaline phosphatase(ALP) in serum were detected. Pathological injuries of livers were detected by hematoxylin-eosin(HE) staining. The levels of malondialdehyde(MDA), superoxide dismutase(SOD), glutathione peroxidase(GSH-Px), and reduced glutathione(GSH) in the liver were measured. Wes-tern blot method was used to detect the expression of nuclear factor erythroid 2-related factor 2(Nrf2), Kelch-like ECH-associated protein 1(Keap1), peroxisome proliferator-activated receptor gamma, coactivator-1 alpha(PGC-1α), heme oxygenase-1(HO-1), and NAD(P)H quinone dehydrogenase 1(NQO1) in livers. Immunofluorescence was used to detect the expression of Nrf2 and PGC-1α in livers. The results indicated that Astragalus membranaceus/Angelica sinensis ratio of 2∶1 and 5∶1 could significantly reduce the levels of serum AST, ALT, and ALP, improve the pathological damage of liver tissue, increase the levels of GSH and GSH-Px, and reduce the content of MDA in liver tissue. Astragalus membranaceus/Angelica sinensis ratio of 1∶1 and 2∶1 could significantly improve the level of SOD. Astragalus membranaceus and Angelica sinensis before and after compatibility significantly increased the protein expression of HO-1 and NQO1, improved the protein expression of Nrf2 and PGC-1α, and decreased the protein expression of Keap1 in liver tissue. The above results confirmed that the compatibility of Astragalus membranaceus and Angelica sinensis had antioxidant effects by re-gulating Keap1/Nrf2/PGC-1α, and the Astragalus membranaceus/Angelica sinensis ratio of 2∶1 and 5∶1 had stronger antioxidant effect and significantly reduced TP-induced hepatoto-xicity.

Adverse effects of cigarette smoke on NO bioavailability: role of arginine metabolism and oxidative stress.

Endothelial dysfunction is a hallmark of cardiovascular disease, and the l-arginine:NO pathway plays a critical role in determining endothelial function. Recent studies suggest that smoking, a well-recognized risk factor for vascular disease, may interfere with l-arginine and NO metabolism; however, this remains poorly characterized. Accordingly, we performed a series of complementary in vivo and in vitro studies to elucidate the mechanism by which cigarette smoke adversely affects endothelial function. In current smokers, plasma levels of asymmetrical dimethyl-arginine (ADMA) were 80% higher (P = 0.01) than nonsmokers, whereas citrulline (17%; P < 0.05) and N-hydroxy-l-arginine (34%; P < 0.05) were significantly lower. Exposure to 10% cigarette smoke extract (CSE) significantly affected endothelial arginine metabolism with reductions in the intracellular content of citrulline (81%), N-hydroxy-l-arginine (57%), and arginine (23%), while increasing ADMA (129%). CSE significantly inhibited (38%) arginine uptake in conjunction with a 34% reduction in expression of the arginine transporter, CAT1. In conjunction with these studies, CSE significantly reduced the activity of eNOS and NO production by endothelial cells, while stimulating the production of reactive oxygen species. In conclusion, cigarette smoke adversely affects the endothelial l-arginine NO synthase pathway, resulting in reducing NO production and elevated oxidative stress. In conjunction, exposure to cigarette smoke increases ADMA concentration, the latter being a risk factor for cardiovascular disease.

Impaired L-arginine transport and endothelial function in hypertensive and genetically predisposed normotensive subjects.

BACKGROUND: Impaired endothelium-dependent NO-mediated vasodilation is a key feature of essential hypertension and may precede the increase in blood pressure. We investigated whether transport of the NO precursor L-arginine is related to decreased endothelial function. METHODS AND RESULTS: Radiotracer kinetics ([3H]L-arginine) were used to measure forearm and peripheral blood mononuclear cell arginine uptake in hypertensive subjects (n=12) and in 2 groups of healthy volunteers with (n=15) and without (n=15) a family history of hypertension. In conjunction, forearm blood flow responses to acetylcholine and sodium nitroprusside were measured before and after a supplemental intra-arterial infusion of L-arginine. In vivo and in vitro measures of L-arginine transport were substantially reduced in the essential hypertension and positive family history groups compared with the negative family history group; however, no difference was detected in peripheral blood mononuclear cell mRNA or protein expression levels for the cationic amino acid transporter CAT-1. Plasma concentrations of L-arginine and N(G),N(G')-dimethylarginine (ADMA) did not differ between groups. L-arginine supplementation improved the response to acetylcholine only in subjects with essential hypertension and positive family history. CONCLUSIONS: Similar to their hypertensive counterparts, normotensive individuals at high risk for the development of hypertension are characterized by impaired L-arginine transport, which may represent the link between a defective L-arginine/NO pathway and the onset of essential hypertension. The observed transport defect is not due to apparent alterations in CAT-1 expression or elevated endogenous ADMA.