Characterization of the MethionineS-Oxidase Activity of Rat Liver and Kidney Microsomes: Immunochemical and Kinetic Evidence for FMO3 Being the Major Catalyst

1996 ◽  
Vol 333 (1) ◽  
pp. 109-116 ◽  
Author(s):  
Renee J. Krause ◽  
Sharon L. Ripp ◽  
Peter J. Sausen ◽  
Lila H. Overby ◽  
Richard M. Philpot ◽  
...  
Keyword(s):  
Rat Liver ◽  
Oxidase Activity ◽  
Liver And Kidney ◽  
Kidney Microsomes

Characterization of a novel non-peptide vasopressin V1 receptor antagonist (OPC-21268) in the rat

1993 ◽  
Vol 138 (2) ◽  
pp. 259-266 ◽  
Author(s):  
L. M. Burrell ◽  
P. A. Phillips ◽  
J. Stephenson ◽  
J. Risvanis ◽  
A.-M. Hutchins ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Rat Liver ◽  
Renal Medulla ◽  
Kinetic Studies ◽  
Dependent Manner ◽  
Kidney Medulla ◽  
Liver And Kidney

ABSTRACT A non-peptide, orally effective, vasopressin (AVP) V1 receptor antagonist 1-{1-[4-(3-acetylaminopropoxy) benzoyl]-4-piperidyl}-3,4-dihydro-2(1H)-quinolinone (OPC-21268) has recently been described. This paper reports the in-vitro and in-vivo characterization of OPC-21268 binding to vasopressin receptors in rat liver and kidney. OPC-21268 caused a concentration-dependent displacement of the selective V1 receptor antagonist radioligand, 125I-labelled [d(CH2)5,sarcosine7]AVP to V1 receptors in both rat liver and kidney medulla membranes. The concentration of OPC-21268 that displaced 50% of specific AVP binding (IC50) was 40±3 nmol/l for liver V1 and 15±2 nmol/l for kidney V1 receptors (mean ± s.e.m.; n = 3). OPC-21268 had little effect on the selective V2 antagonist radioligand [3H]desGly-NH29[d(CH2)5,d-Ile2,Ile4] AVP binding to V2 receptors in renal medulla membranes (IC50 >0·1 mmol/l). After oral administration to rats, OPC-21268 was an effective V1 antagonist in a time- and dose-dependent manner. Binding kinetic studies showed that OPC-21268 acted as a competitive antagonist at the liver V1 receptor in vitro and in vivo, in addition to its in-vitro competitive effects at the renal V1 receptor. OPC-21268 shows promise as an orally active V1 antagonist. Journal of Endocrinology (1993) 138, 259–266

scholarly journals Characterization of the enzymic capacity for cysteine desulphhydration in liver and kidney of the rat

1982 ◽  
Vol 206 (2) ◽  
pp. 267-277 ◽  
Author(s):  
M H Stipanuk ◽  
P W Beck
Keyword(s):  
Urinary Excretion ◽  
Rat Liver ◽  
Cystathionine Beta Synthase ◽  
Liver And Kidney ◽  
H2s Production

The contribution of cystathionine gamma-lyase, cystathionine beta-synthase and cysteine aminotransferase coupled to 3-mercaptopyruvate sulphurtransferase to cysteine desulphhydration in rat liver and kidney was assessed with four different assay systems. Cystathionine gamma-lyase and cystathionine beta-synthase were active when homogenates were incubated with 280 mM-L-cysteine and 3 mM-pyridoxal 5′-phosphate at pH 7.8. Cysteine aminotransferase in combination with 3-mercaptopyruvate sulphurtransferase catalysed essentially all of the H2S production from cysteine at pH 9.7 with 160 mM-L-cysteine, 2 mM-pyridoxal 5′-phosphate, 3 mM-2-oxoglutarate and 3 mM-dithiothreitol. At more-physiological concentrations of cysteine (2 mM) cystathionine gamma-lyase and cystathionine beta-synthase both appeared to be active in cysteine desulphhydration, whereas the aminotransferase pathway did not. The effect of inhibition of cystathionine gamma-lyase by a suicide inactivator, propargylglycine, in the intact rat was also investigated; there was no significant effect of propargylglycine administration on the urinary excretion of total 35S, 35SO4(2-) or [35S]taurine formed from labelled dietary cysteine.

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