scholarly journals Nitroglycerin metabolism in vascular tissue: role of glutathione S-transferases and relationship between NO. and NO2– formation

1993 ◽  
Vol 292 (2) ◽  
pp. 545-550 ◽  
Author(s):  
M A Kurz ◽  
T D Boyer ◽  
R Whalen ◽  
T E Peterson ◽  
D G Harrison
Keyword(s):  
Vascular Tissue ◽  
Potent Inhibitor ◽  
Metabolic Process ◽  
No Production ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
No Release ◽  
Glutathione S Transferases ◽  
No2 Formation

Nitroglycerin is a commonly employed pharmacological agent which produces vasodilatation by release of nitric oxide (NO.). The mechanism by which nitroglycerin releases NO. remains undefined. Recently, glutathione S-transferases have been implicated as important contributors to this process. They are known to release NO2- from nitroglycerin, but have not been shown to release NO.. The present studies were designed to examine the role of endogenous glutathione S-transferases in this metabolic process. Homogenates of dog carotid artery were incubated anaerobically with nitroglycerin, and NO. and NO2- production was determined by chemiluminescence. The role of glutathione S-transferases was studied by incubating homogenates with nitroglycerin in the presence of 1 mM GSH or 1 mM S-hexyl-glutathione, a potent inhibitor of glutathione S-transferases. Homogenates released 163 pmol of NO./h per mg of protein from nitroglycerin, and 2370 pmol of NO2-/h per mg. Adding GSH decreased NO. production by 82% and increased NO2- production by 98%. S-Hexylglutathione inhibited glutathione S-transferase activity by 96% and decreased NO2- production by 78%, but had no effect on NO. release. A linear relationship between glutathione S-transferase activity and NO2- production was observed, whereas glutathione S-transferase activity and NO. release were unrelated. Western-blot analysis demonstrated that dog carotid vascular smooth muscle contained Pi and Mu forms of glutathione S-transferases, with a predominance of the former. Purified preparations of human Pi and rat Mu isoforms metabolized nitroglycerin only to NO2- and not to NO.. On the basis of these findings, we conclude that (1) glutathione S-transferases do not contribute to the bioconversion of nitroglycerin to NO., but instead act as a degradative pathway for nitroglycerin, and (2) the release of NO. from nitroglycerin is not dependent on the formation of NO2-.

scholarly journals The presence and longitudinal distribution of the glutathione S-transferase in rat epididymis and vas deferens

1980 ◽  
Vol 189 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Barbara F. Hales ◽  
Christiane Hachey ◽  
Bernard Robaire
Keyword(s):  
Substrate Specificity ◽  
Isoelectric Focusing ◽  
Vas Deferens ◽  
Longitudinal Distribution ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
Potential Significance ◽  
Glutathione S Transferases ◽  
Rat Epididymis ◽  
First Time

The presence of the glutathione S-transferases, enzymes that catalyse the conjugation of glutathione with a variety of compounds, is reported here, for the first time, in the mammalian epididymis–vas deferens. These glutathione S-transferases, approx. 50% of those from rat liver on a per-mg-of-protein basis, are resolved by isoelectric focusing into six peaks, each with a characteristic isoelectric point and substrate specificity. By these same criteria, the first three peaks (pI 8.9, 8.2 and 7.8) can be identified as transferases B, A and C respectively. The fifth peak (pI7.2) may correspond to transferase M; the fourth (pI7.5) and sixth (pI7.0) peaks do not correspond to previously described transferases. The distribution of transferase activity towards any one substrate studied differs in sequential sections of the epididymis and vas deferens; in addition, the longitudinal-distribution pattern differs for each of the three substrates studied. Isoelectric focusing of the cytosol fractions of the different sections further substantiates these observations. The potential significance of these enzymes and of their distribution in terms of epididymal function, maturation of spermatozoa, is discussed.

Effect of inhibitors of glutathione S-transferase on glyceryl trinitrate activity in isolated rat aorta

1993 ◽  
Vol 71 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Rita Nigam ◽  
Tracy Whiting ◽  
Brian M. Bennett
Keyword(s):  
Glyceryl Trinitrate ◽  
Cyclic Gmp ◽  
Guanylyl Cyclase ◽  
Rat Aorta ◽  
Supernatant Fraction ◽  
Organic Nitrates ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
Glutathione S Transferases

We investigated the role of glutathione S-transferases (enzymes known to biotransform organic nitrates) in the vascular action of glyceryl trinitrate (GTN). Relaxation of phenylephrine-contracted rat aortic strips was assessed in the presence or absence of the glutathione S-transferase inhibitors Basilen Blue, bromosulfophthalein, Rose Bengal, hematin, chlorotriphenyltin, and (octyloxy)benzoylvinylglutathione. Whereas none of the inhibitors increased the EC50 for GTN relaxation, glutathione S-transferase activity in the 100 000 × g supernatant fraction of rat aorta was inhibited markedly by most of the inhibitors. In addition, GTN-stimulated activation of aortic guanylyl cyclase in broken-cell preparations was attenuated by all of the glutathione S-transferase inhibitors, suggesting a direct inhibitory action on guanylyl cyclase. In other experiments using aortic strips preexposed to phenylephrine, the inhibitors had no effect on GTN-induced cyclic GMP accumulation or on vascular biotransformation of GTN. In contrast, both Basilen Blue and bromosulfophthalein significantly inhibited GTN-induced relaxation of K+-contracted aortic strips, and Basilen Blue significantly inhibited GTN biotransformation in aortic strips preexposed to 25 mM K+. This may be due to a more favourable electrochemical gradient for entry of the inhibitors into membrane-depolarized tissues. We conclude that vascular glutathione S-transferases play a role in mediating the vasodilator actions of GTN in intact tissues in vitro, but that this appears to depend upon the nature of the contractile agent used in such studies.Key words: glyceryl trinitrate, glutathione S-transferase, cyclic GMP, vascular smooth muscle, biotransformation.

scholarly journals In vivo Role of Cytochrome P450 2E1 and Glutathione-S-Transferase Activity for Acrylamide Toxicokinetics in Humans

2009 ◽  
Vol 18 (2) ◽  
pp. 433-443 ◽  
Author(s):  
Oxana Doroshyenko ◽  
Uwe Fuhr ◽  
Daria Kunz ◽  
Dorothee Frank ◽  
Martina Kinzig ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Transferase Activity ◽  
Cytochrome P450 2E1 ◽  
Glutathione S Transferase

scholarly journals Cathepsin B-Mediated NLRP3 Inflammasome Formation and Activation in Angiotensin II -Induced Hypertensive Mice: Role of Macrophage Digestion Dysfunction

2018 ◽  
Vol 50 (4) ◽  
pp. 1585-1600 ◽  
Author(s):  
Dawei Lian ◽  
Jieqing Lai ◽  
Yanjiao Wu ◽  
Lei Wang ◽  
Yongjun Chen ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Gene Silencing ◽  
Nlrp3 Inflammasome ◽  
Cathepsin B ◽  
Lysosomal Membrane ◽  
No Production ◽  
Ang Ii ◽  
No Release ◽  
Nlrp3 Inflammasomes

Background/Aims: Angiotensin II (Ang II) is an octapeptide hormone that plays a significant role in mediating hypertension. Although hypertension is considered a chronic inflammatory disease, the molecular basis of the sterile inflammatory response involved in hypertension remains unclear. Methods: We investigated the role of macrophage NLRP3 inflammasomes in engulfing and digesting microbes, a key macrophage function, and in early onset of hypertension-associated macrophage injury using biochemical analyses, gene silencing, molecular biotechnology, immunofluorescence, and microbiology. Results: Ang II stimulation decreased nitric oxide (NO) release and macrophage digestion in cultured THP-1 cells and markedly increased NLRP3 inflammasome formation and activation. NO release and macrophage digestion were restored by NLRP3 inflammasome inhibition with isoliquiritigenin and gene silencing. This Ang II-induced upregulation of NLRP3 inflammasomes in macrophages was attributed to lysosomal damage and release of cathepsin B. Mechanistically, losartan, a nonpeptide Ang II receptor antagonist, decreased Ang II-induced NLRP3 inflammasome activation, lysosomal membrane permeability, lysosomal cathepsin B release, and macrophage digestion dysfunction. Similarly, Ang II-induced macrophage microbe digestion and NO production, which were blocked by ATI gene silencing. In addition, in vivo experiments showed that the bacteria scavenging function was clearly decreased in macrophages from Ang II-induced hypertensive mice. Conclusion: Angiotensin II enhances lysosomal membrane permeabilization and the consequent release of lysosomal cathepsin B, resulting in activation of the macrophage NLRP3 inflammasome. This may contribute to NO mediation of dysfunction in digesting microbes.

scholarly journals Comparison of renal and hepatic glutathione S-transferases in the rat

1976 ◽  
Vol 158 (2) ◽  
pp. 243-248 ◽  
Author(s):  
N Kaplowitz ◽  
G Clifton ◽  
J Kuhlenkamp ◽  
J D Wallin
Keyword(s):  
Organic Anion ◽  
Gel Filtration ◽  
Competitive Inhibitor ◽  
Transferase Activity ◽  
Close Correspondence ◽  
Glutathione S Transferase ◽  
Competitive Inhibitors ◽  
Liver And Kidney ◽  
Glutathione S Transferases

Renal and hepatic GSH (reduced glutathione) S-transferase were compared with respect to substrate and inhibitory kinetics and hormonal influences in vivo. An example of each of five classes of substrates (aryl, aralkyl, epoxide, alkyl and alkene) was used. In the gel filtration of renal or hepatic cytosol, an identical elution volume was found for all the transferase activities. Close correspondence in Km values was found for aryl, epoxide- and alkyl-transferase activities, with only the aralkyl activity significantly lower in kidney. Probenecid and p-aminohippurate were competitive inhibitors of renal aryl-, aralkyl-, epoxide- and alkyl-transferase activities and inhibited renal alkene activity. Close correspondence in Ki values for inhibition by probenecid of these activities in kidney and liver was found. In addition, furosemide was a potent competitive inhibitor of renal alkyl-transferase activity. Hypophysectomy resulted in significant increases in aryl-, araklyl-, and expoxide-transferase activities in liver and kidney. The hypophysectomy-induced increases in renal aryl- and aralkyl-transferase activities (approx. 100%) were more than twofold greater than increases in hepatic activities (approx. 40%). Administration of thyroxine prevented the hypophysectomy-induced increase in aryltransferase activity in both kidney and liver. The renal GSH S-transferases, in view of similarities to the hepatic activities, may play a role as cytoplasmic organic-anion receptors, as previously proposed for the hepatic enzymes.

Tissue Distribution and Properties of Glutathione S-transferases in Micromelalopha troglodyta (Lepidoptera: Notodontidae)

2008 ◽  
Vol 43 (3) ◽  
pp. 268-278 ◽  
Author(s):  
Fang Tang ◽  
Xiu-Bo Zhang ◽  
Yu-Sheng Liu ◽  
Xi-Wu Gao
Keyword(s):  
Tissue Distribution ◽  
Tannic Acid ◽  
Fat Body ◽  
Inhibitory Effect ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
Important Pest ◽  
Glutathione S Transferases ◽  
Gst Activity ◽  
Different Tissues

The small prominent, Micromelalopha troglodyta (Graeser) (Lepidoptera: Notodontidae), is an important pest of poplar in China. Glutathione S-transferases are known to be responsible for adaptation mechanisms of M. troglodyta. Thus, the tissue distribution and kinetic constants of glutathione S-transferase activity in the small prominent were studied. Significant differences in glutathione S-transferase (GST) activity and distribution percentages of GST activity and kinetic characteristics were observed among 4 tissues (head, midgut, fat body and integument). Furthermore, the inhibition of glutathione S-transferase activity in 4 tissues by 21 inhibitors was conducted. The results showed the inhibition of GST activity of different tissues by 21 inhibitors is different. For GST activity in heads, chlorpyrifos, profenofos, lambda-cyhalothrin, fipronil and quercetin were the best inhibitors tested. Tannic acid was the most potent inhibitor of midgut GST activity. In the fat body, GST activity was inhibited most by tannic acid, chlorpyrifos and profenofos. The inhibitory effect of profenofos and phoxim was highest for GST activity in the integument. Our results showed that glutathione S-transferases in different tissues are qualitatively different in isozyme composition and thus different in sensitivity to inhibitors.

Role of Calcium Fluxes in the Action of Glucagon on Cytosolic Glutathione S-Transferase Activity in Rat Liver Slices

1995 ◽  
Vol 77 (5) ◽  
pp. 316-319 ◽  
Author(s):  
Juan A. Monti ◽  
Cristina E. Carnovale ◽  
Celina Scapini ◽  
Cristián Favre ◽  
María C. Carrillo
Keyword(s):  
Rat Liver ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
Calcium Fluxes ◽  
Liver Slices ◽  
Cytosolic Glutathione

scholarly journals Cholic acid binding by glutathione S-transferases from rat liver cytosol

1980 ◽  
Vol 185 (1) ◽  
pp. 83-87 ◽  
Author(s):  
J D Hayes ◽  
R C Strange ◽  
I W Percy-Robb
Keyword(s):  
Bile Acid ◽  
Cholic Acid ◽  
Reduced Glutathione ◽  
Binding Activity ◽  
Transferase Activity ◽  
Glutathione S Transferase ◽  
Liver Cytosol ◽  
Glutathione S Transferases ◽  
Rat Livers ◽  
Rat Liver Cytosol

Cholic acid-binding activity in cytosol from rat livers appears to be mainly associated with enzymes having glutathione S-transferase activity; at least four of the enzymes in this group can bind the bile acid. Examination of the subunit compositions of different glutathione S-transferases indicated that cholic acid binding and the ability to conjugate reduced glutathione with 1,2-dichloro-4-nitrobenzene may be ascribed to different subunits.

scholarly journals Nonhistone protein BA is a glutathione S-transferase localized to interchromatinic regions of the cell nucleus.

1986 ◽  
Vol 102 (2) ◽  
pp. 600-609 ◽  
Author(s):  
C F Bennett ◽  
D L Spector ◽  
L C Yeoman
Keyword(s):  
Rat Liver ◽  
Cell Nucleus ◽  
Polyacrylamide Gel Electrophoresis ◽  
Rnase A ◽  
Transferase Activity ◽  
Immunoperoxidase Technique ◽  
Glutathione S Transferase ◽  
Nonhistone Protein ◽  
Glutathione S Transferases ◽  
Nuclear Domains

A DNA-binding nonhistone protein, protein BA, was previously demonstrated to co-localize with U-snRNPs within discrete nuclear domains (Bennett, F. C., and L. C. Yeoman, 1985, Exp. Cell Res., 157:379-386). To further define the association of protein BA and U-snRNPs within these discrete nuclear domains, cells were fractionated in situ and the localization of the antigens determined by double-labeled immunofluorescence. Protein BA was extracted from the nucleus with the 2.0 M NaCl soluble chromatin fraction, while U-snRNPs were only partially extracted from the 2.0 M NaCl-resistant nuclear structures. U-snRNPs were extracted from the residual nuclear material by combined DNase I/RNase A digestions. Using an indirect immunoperoxidase technique and electron microscopy, protein BA was localized to interchromatinic regions of the cell nucleus. Protein BA was noted to share a number of chemical and physical properties with a family of cytoplasmic enzymes, the glutathione S-transferases. Comparison of the published amino acid composition of protein BA and glutathione S-transferases showed marked similarities. Nonhistone protein BA isolated from saline-EDTA nuclear extracts exhibited glutathione S-transferase activity with a variety of substrates. Substrate specificity and subunit analysis by SDS polyacrylamide gel electrophoresis revealed that it was a mixture of several glutathione S-transferase isoenzymes. Protein BA isolated from rat liver chromatin was shown by immunoblotting and peptide mapping techniques to be two glutathione S-transferase isoenzymes composed of the Yb and Yb' subunits. Glutathione S-transferase Yb subunits were demonstrated to be both nuclear and cytoplasmic proteins by indirect immunolocalization on rat liver cryosections. The identification of protein BA as glutathione S-transferase suggests that this family of multifunctional enzymes may play an important role in those nuclear domains containing U-snRNPs.

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