No abstract

were reduced following co-incubation with Nrnitro-L-arginine methylester (L-NAME; 1 mM), NGnitro-Larginine (L-NOARG; mM) and L-canavanine (1 mM) to 47.1 ± 6.2, 24.7 ± 3.6 and 12.5 ± 2.8% of control levels (P< 0.001; n = 9). ADMA (1 mM; n = 3) reduced intracellular [14C]-citrulline levels to 4 ± 4% of control (P<0.01) but SDMA (1 mM; n = 3) had no effect. 5 The accumulation of endogenously synthesized ADMA in the culture supernatant of SGHEC-7 cells was increased by co-incubation with L-NMMA (1 mM) from 1.98 ± 0.08 to 2.74 ± 0.36 nmol mg-cell protein, an increase of 40%. 6 These results demonstrate that human vasculature possesses an enzyme which has similar properties to dimethylarginase; human endothelial cells and human saphenous vein metabolize L-NMMA to citrulline via a process inhibited by ADMA but not SDMA. The increase in endothelium-derived ADMA following co-incubation with L-NMMA is consistent with competition between ADMA and L-NMMA for dimethylarginase. Inhibition of this enzyme might increase the intracellular concentration of ADMA, an endogenously produced compound that inhibits nitric oxide synthesis.

No abstract

No abstract

No abstract