Vitamin E protects porcine but not bovine cultured aortic endothelial cells from oxygen-derived free radical injury due to hydrogen peroxide

The antioxidative effects of vitamin E (VE) are well known and have been demonstrated in in vitro studies. Since we previously observed that dextran sulfate was markedly more protective of porcine versus bovine aortic endothelial cells when damaged by hydrogen peroxide (H2O2), our objectives were to determine if a similar species difference could be observed with VE. The effects of VE or Trolox (a more water-soluble VE) against oxygen-derived free radical (OFR) injury produced by H2O2 was studied in porcine aortic endothelium (PAE) vs. bovine aortic endothelium (BAE) and bovine brain microvessel endothelium (BBME). VE or Trolox was added to culture medium for at least 24 h prior or immediately prior to H2O2 addition. In PAE, pretreatment with VE dissolved in either ethanol (VE-EtOH) or Tween 20 (VE-Tween 20), or Trolox dissolved in DMSO (Trolox-DMSO) was protective, shown by increased percent viable cells and reduced lactate dehydrogenase (LDH) release. EtOH, Tween 20 or DMSO alone was protective in PAE although DMSO or Tween 20 alone was less effective than when added with VE. VE-Tween 20 or Trolox-DMSO protected PAE when added just prior to H2O2 injury, but protection was significantly less than with pretreatment. DMSO immediately prior to H2O2 injury had no protective effect. Tween 20 immediately prior resulted in complete cell death. In BAE and BBME, pretreatment with VE-EtOH, EtOH, Trolox-DMSO, or DMSO alone had little or no protective effect. Pretreatment with VE-Tween 20 or Tween-20 alone was protective of BAE with Tween 20 being more effective than VE-Tween 20 suggesting that Tween 20 was the protective agent. These studies show that the protective effects of VE and Trolox as well as DMSO, EtOH, and Tween-20 are species dependent.