Nω-Nitro-L-arginine: a potent inhibitor of the L-arginine-dependent soluble guanylate cyclase activation pathway in LLC-PK1 cells

1990 ◽  
Vol 68 (6) ◽  
pp. 749-751 ◽  
Author(s):  
Kunio Ishii ◽  
James F. Kerwin Jr. ◽  
Ferid Murad
Keyword(s):  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Soluble Guanylate Cyclase ◽  
Potent Inhibitor ◽  
Specific Inhibitor ◽  
Cell Types ◽  
Porcine Kidney ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Guanylate Cyclase Activation

Oxytocin increased cyclic GMP levels in LLC-PK1 porcine kidney epithelial cells through activation of soluble guanylate cyclase. NG-Monomethyl-L-arginine and Nω-nitro-L-arginine inhibited oxytocin (10 μM) induced cyclic GMP accumulation with IC50 values of 2.3 μM and 140 nM, respectively, and the inhibition was prevented with L-arginine. Both inhibitors at 100 μM lowered the basal levels of cyclic GMP, but did not affect those induced by 1 μM sodium nitroprusside and 100 nM atrial natriuretic factor. These data support our hypothesis that an endothelium-derived relaxing factor-like substance is formed as the endogenous activator of soluble guanylate cyclase in an L-arginine-dependent fashion in various cell types. Nω-Nitro-L-arginine is 16 times more potent than NG-monomethyl-L-arginine as a specific inhibitor of this pathway in LLC-PK1 cells.Key words: porcine kidney epithelial (LLC-PK1) cells, cyclic GMP, Nω-nitro-L-arginine, NG-monomethyl-L-arginine, endothelium-derived relaxing factor.

scholarly journals N-hydroxylamine is not an intermediate in the conversion of l-arginine to an activator of soluble guanylate cyclase in neuroblastoma N1E-115 cells

1991 ◽  
Vol 273 (3) ◽  
pp. 547-552 ◽  
Author(s):  
S Pou ◽  
W S Pou ◽  
G M Rosen ◽  
E E el-Fakahany
Keyword(s):  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Soluble Guanylate Cyclase ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Intact Cells ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Dose Dependent

This study evaluates the role of N-hydroxylamine (NH2OH) in activating soluble guanylate cyclase in the mouse neuroblastoma clone N1E-115. It has been proposed that NH2OH is a putative intermediate in the biochemical pathway for the generation of nitric oxide (NO)/endothelium-derived relaxing factor (EDRF) from L-arginine. NH2OH caused a time- and concentration-dependent increase in cyclic GMP formation in intact cells. This response was not dependent on Ca2+. In cytosol preparations the activation of guanylate cyclase by L-arginine was dose-dependent and required Ca2+ and NADPH. In contrast, NH2OH itself did not activate cytosolic guanylate cyclase but it inhibited the basal activity of this enzyme in a concentration-dependent manner. The formation of cyclic GMP in the cytosolic fractions in response to NH2OH required the addition of catalase and H2O2. On the other hand, catalase and/or H2O2 lead to a decrease in L-arginine-induced cyclic GMP formation. Furthermore, NH2OH inhibited L-arginine- and sodium nitroprusside-induced cyclic GMP formation in the cytosol. The inhibition of L-arginine-induced cyclic GMP formation in the cytosol by NH2OH was not reversed by the addition of superoxide dismutase. These data strongly suggest that NH2OH is not a putative intermediate in the metabolism of L-arginine to an activator of guanylate cyclase.

Oxygen modulates endothelium-derived relaxing factor production in fetal pulmonary arteries

1992 ◽  
Vol 262 (2) ◽  
pp. H355-H364 ◽  
Author(s):  
P. W. Shaul ◽  
M. A. Farrar ◽  
T. M. Zellers
Keyword(s):  
Oxygen Tension ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Arteries ◽  
Mesenteric Arteries ◽  
Cgmp Production ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Ovine Fetal ◽  
Endothelium Dependent Relaxation

Alterations in endothelium-derived relaxing factor (EDRF) production or mechanism of action may be involved in the responses of the developing pulmonary vasculature to changes in oxygenation. In this study the effects of acute changes in in vitro oxygen tension on EDRF production were determined in isolated segments of ovine fetal intrapulmonary arteries (4th generation) obtained at 125-135 days of gestation (term 144 +/- 4 days). EDRF production was assessed by measuring segment guanosine 3',5'-cyclic monophosphate (cGMP) accumulation in the presence of a phosphodiesterase inhibitor. Basal (nonstimulated) cGMP production and cGMP production with acetylcholine (ACh) stimulation were dependent on the presence of the endothelium, on the availability of L-arginine, and on soluble guanylate cyclase activity, confirming that they were indicative of EDRF production. cGMP production with sodium nitroprusside (SNP) was used to discriminate changes in the sensitivity of soluble guanylate cyclase with varying conditions. With decreasing oxygen tension, basal and ACh-stimulated cGMP production were attenuated, whereas cGMP production with SNP was not, indicating oxygen modulation of EDRF production. Studies of endothelium-dependent relaxation yielded comparable findings in that the response to ACh was attenuated, but that to SNP was not altered by decreased oxygenation. In addition, the decline in endothelium-dependent relaxation with decreased oxygen tension was rapidly reversed when oxygenation was increased. Parallel experiments examining cGMP production in similarly sized mesenteric arteries revealed that the effect of oxygen on pulmonary artery EDRF production may be specific to that vascular bed. These findings indicate that oxygen selectively modulates EDRF production and endothelium-dependent relaxation in ovine fetal pulmonary arteries. Direct effects of oxygen on EDRF production may at least partially underlie the responses of the developing pulmonary circulation to changes in oxygenation.

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