title: Catalytic conversion of L-arginine to nitrate by platinum electrodes.
abstract: Platinum electrodes (PLE) have been used recently to study the physiologic effects of the enzymatic conversion of L-arginine (L-arg) to nitric oxide (NO) by nitric oxide synthase (NOS). We sought to determine if PLE alone could catalytically convert L-arg to NO without NOS. Accordingly, NO2- + NO3- levels (NOx) were measured by HPLC from a physiologic Tyrode's buffer in the presence and absence of electrical stimulation with PLE or silver chloride electrodes (SCE) for 10 min (n = 6 for each condition). PLE stimulated at 1Hz produced 24 +/- 0.7 and 15.4 +/- 2.8 microM NOx from D-arg and L-arg (100mM) respectively. PLE + L-arg stimulated from 0 to 5 Hz produced increasing NOx (2.9 +/- 0.27;15.4 +/- 2.8;19.7 +/- 4;32 +/- 5;37 +/- 6.2;43 +/- 7 microM). SCE+L-arg showed no increase in NOx above background. The addition of 1% BSA to the Tyrode's buffer further increased NOx levels. NO2- levels were undetectable, indicating all NOx levels were NO3-. We conclude that PLE can catalytically convert L-Arg to NO3- via electron transfer without NOS.
authors.affiliation: Department of Medicine, University of Pittsburgh School of Medicine, University of Pittsburgh Medical Center, PA 15213-2582.
authors.forename: M S
authors.initials: MS
authors.lastname: Finkel
authors.forename: C V
authors.initials: CV
authors.lastname: Oddis
authors.forename: C F
authors.initials: CF
authors.lastname: Nopper
authors.forename: R L
authors.initials: RL
authors.lastname: Simmons
authors.forename: B G
authors.initials: BG
authors.lastname: Hattler
mesh_terms: D001120:Arginine / Q000737:chemistry*; D002384:Catalysis; D004566:Electrodes; D009566:Nitrates / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*
chemical_list: D009566:Nitrates; D010984:Platinum; D001120:Arginine