The Inhibition of the Constitutive Bovine Endothelial Nitric Oxide Synthase by Imidazole and Indazole Agents

Wolff, Donald J.; Lubeskie, Andrew; Umansky, Samuil R.

doi:10.1006/abbi.1994.1454

Cited by 69 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The kinetic analysis of platelet NOS activity was based on Garvey et al (1994) and Wolf et al (1994) by using three different L-arginine concentrations with a fixed concentration of 3 H-arginine (0.5 μCi). In order to have high enough arginine concentration in the assay, 3 Harginine can be mixed with non-radioactive arginine.…”

Section: Discussionmentioning

confidence: 99%

Human platelet nitric oxide synthase activity: an optimized method

Kawamato¹,

Glezer²,

Munhoz³

et al. 2002

Rev. Bras. Cienc. Farm.

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

Human platelet nitric oxide synthase activity: an optimized method

Kawamato¹,

Glezer²,

Munhoz³

et al. 2002

Rev. Bras. Cienc. Farm.

View full text Add to dashboard Cite

show abstract

“…However, it has been shown that inhibition of nNOS by 7-nitroindazole was competitive vs L-arginine and vs BH4. Thus, the presence of high concentrations of BH4 in the assay medium would diminish its sensitivity to inhibition (Wolff et al, 1994). In fact, Ki values of 35 gM for 7-nitroindazole have been reported at saturating concentrations of BH4 (Wolff et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Characterization of nitric oxide synthase activity in sheep urinary tract: functional implications

Garcia-Pascual

Costa

Labadía

et al. 1996

British J Pharmacology

View full text Add to dashboard Cite

1 To define further the role of nitric oxide (NO) in urinary tract function, we have measured the presence of nitric oxide synthase (NOS) activity, and its relationship with functional NO-mediated responses to electrical field stimulation (EFS) in the urethra, the detrusor and the ureter from sheep. NOS activity was assayed by the conversion of L-['4C]-arginine to L-['4C]-citrulline. Endogenous production of citrulline was confirmed by thin layer chromatography. 2 NOS enzymatic activity was detected in the cytosolic fraction from tissue homogenates with the following regional distribution (pmol citrulline mg-' protein min-'): urethra (33 + 3.3), detrusor (13.1 + 1.1) and ureter (1.5 + 0.2). No activity was detected in the particulate fraction of any region. 3 NOS activity was dependent on Ca2+-calmodulin and required exogenously added NADPH and tetrahydrobyopterin (BH4) for maximal activity. Exclusion of calmodulin from the incubation mixture did not modify NOS activity, but it was significantly reduced in the presence of the calmodulin antagonist, calmidazolium, suggesting the presence of enough endogenous calmodulin to sustain the observed NOS activity. 4 NOS activity was inhibited to a greater extent by NG-nitro-L-arginine (L-NOARG) and its methyl ester (L-NAME) than by NG-monomethyl-L-arginine (L-NMMA), while 7-nitroindazole (7-NI) was a weak inhibitor and L-cannavine had no effect. 5 Citrulline formation could be inhibited by superoxide dismutase in an oxyhaemoglobin-sensitive manner, suggesting feedback inhibition of NOS by NO. 6 EFS induced prominent NO-mediated relaxations in the urethra while minor or no responses were observed in the detrusor and the ureter, respectively. Urethral relaxations to EFS were inhibited by NOS inhibitors with the rank order of potency: L-NOARG = L-NAME>7-NI> L-NMMA. 7In conclusion, we have demonstrated the presence of NO-synthesizing enzymatic activity in the sheep urinary tract which shows similar characteristics to the constitutive NOS isoform found in brain. We suggest that the enzymatic activity measured in the urethral muscle layer may account for the NOmediated urethral relaxation during micturition whereas regulation of detrusor and ureteral motor function by NOS containing nerves is less likely. Keywords: Nitric oxide; nitric oxide synthase; urethra; detrusor; ureter; nitrergic relaxation; urinary tract Introduction It has been suggested that nitric oxide (NO) has important regulatory functions in the urinary tract acting as a nonadrenergic, non-cholinergic (NANC)-relaxant transmitter. Specially relevant is the proposed role of NO in mediating the decrease in outlet resistance which accompanies micturition (Andersson, 1993). A rich supply of nitrergic nerves has been identified by NADPH-diaphorase histochemistry and nitric oxide synthase (NOS) immunohistochemistry in the outflow region (urethra, bladder neck and bladder base or trigone) of several species including rat (McNeill et al., 1992), pig (Persson et al., 1993), sheep (Triguero et al., 1993 and human (Sme...

show abstract

“…Numerous pathologies are attributed to excess NO production by iNOS (13)(14)(15)(16) and have led to a quest for specific inhibitors of this isoform. Work has focused on a broad range of molecules including substrate analogs, guanidine derivatives, thioureas, and heterocycles, with some specific inhibitors beginning to emerge (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27).…”

Section: Nitric Oxide (No)mentioning

confidence: 99%

“…A study of iNOS dimerization as promoted by L-Arg showed that its effect was stereospecific but not unique, because several LArg and guanidine analogs that bind to the iNOS dimer also promoted dimer assembly (41,56). Two substrate analogs that exhibit greater affinity toward the iNOS dimer than L-Arg, N -amino-L-Arg and L-thiocitrulline (21,24), did not promote dimer assembly, suggesting they might function as antagonists. However, they were incapable of blocking dimer assembly in the presence of excess L-Arg (56), consistent with their sharing a common binding site but being generally unable to bind to iNOS monomers (32,48,49).…”

Section: Nitric Oxide (No)mentioning

confidence: 99%