Article date: July 2009
By: Z Luo, Y Chen, S Chen, WJ Welch, BT Andresen, PA Jose, CS Wilcox in Volume 157, Issue 6, pages 935-943
Background and purpose: We compared the dose‐dependent reductions in cellular superoxide anion (O2‐) by catalytic agents: superoxide dismutase (SOD), polyethylene glycol (PEG)‐SOD and the nitroxide 4‐hydroxy‐2,2,6,6,‐tetramethylpiperidine‐1‐oxyl (tempol) with uncharacterized antioxidants: 5,10,15,20‐tetrakis (4‐sulphonatophenyl) porphyrinate iron (III)(Fe‐TTPS), (‐)‐cis‐3,3′,4′,5,7‐pentahydroxyflavane (2R,3R)‐2‐(3,4‐dihydroxyphenyl)‐3,4‐dihydro‐1(2H)‐benzopyran‐3,5,7‐triol (‐epicatechin), 2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one (ebselen) and N‐acetyl‐L‐cysteine (NAC) with the spin trap nitroblue tetrazolium (NBT) and with the vitamins or their analogues: ascorbate, α‐tocopherol and 6‐hydroxy‐2,5,7,8‐tetramethylkroman‐2‐carboxy acid (trolox).
Experimental approach: O2‐ was generated in primary cultures of angiotensin II‐stimulated preglomerular vascular smooth muscle cells from spontaneously hypertensive rats and detected by lucigenin‐enhanced chemiluminescence.
Key results: SOD, PEG‐SOD, NAC and tempol produced a similar maximum inhibition of O2‐ of 80–90%. ‐Epicatechin, NBT, ebselen and Fe‐TTPS were significantly (P < 0.0125) less effective (50–70%), whereas trolox, α‐tocopherol and ascorbate had little action even over 24 h of incubation (<31%). Effectiveness in disrupted and intact cells was similar for the permeable agents, PEG‐SOD and tempol, but was enhanced for SOD. Generation of O2‐ was increased by NAC and NBT at low concentrations but reduced at high concentrations.
Conclusions and implications: Maximum effectiveness against cellular production of O2‐ requires cell membrane permeability and catalytic action as exemplified by PEG‐SOD or tempol. NAC and NBT have biphasic effects on O2‐ production. Vitamins C and E or analogues have low efficacy.
DOI: 10.1111/j.1476-5381.2009.00259.x
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