Damages Of Paraoxon On Vascular Emdothelial Cell And Protective Effects Of Captopril As Well As Exploration On Their Mechanims

AIM:To examine whether paraoxon(PO),an active component of organophosphate,can directly cause injuries of vascular endothelial cells and to explore the protective effects of captopril(Cap)on vascular endothelial cells damage induced by paraoxon and the potential mechanisms.METHODS:(1)Rat isolated vascular rings experiment in vitro, isolated rat aortic rings were prepared according to previous method.To explore the mechanisms of endothelial cell damage induced by PO,the rings were respectively incubated with alone PO at the concentration of 0.0363～36.3μM),PO(3.63μM)plus catalase(CAT),PO(3.63μM)plus L-arginine(L-Arg),PO(3.63μM)plus atropine(ATP)for 30 min.The AChinduced endothelium-dependent relaxation(EDR),sodium nitroprusside (SNP)-induced endothelium-independent relaxation and the vascular tissue biochemical reference were measured in rat vascular tissue.To explore the mechanisms of protective effects of Cap on impaired vascular endothelial function induced by PO,the rings were respectively incubated with alone Cap(10μM)and PO(3.63μM),Cap(0.1,1,10μM)plus PO (36.3μM),PO(3.63μM)plus CAT,PO(3.63μM)plus superoxide dismutase (SOD),PO(3.63μM)plus enalaprilat(Ena),PO(3.63μM)plus Cap (10μM)and cystatin(PHMB)for 30 min.The ACh-induced EDR,sodium nitroprusside(SNP)-induced endothelium-independent relaxation and the vascular tissue biochemical index were measured in rat vascular tissus.(2) In cultured cell experiment in vitro,cultured HUVEC were used to detect the endothelium cell monolayer permeability and the mechanisms of vascular endothelial cell damage induced by PO,the HUVEC were respectively incubated with PO(0.0363～36.3μM),histamine(HA),PO (3.63μM)plus CAT for 30 min.HUVEC monolayer permeability, endothelial cell activity,biochemical index in cell cultured fluid and morphology of the endothelial cell were examined.To explore the protective effects of captopril on impaired vascular endothelial function induced by PO,the HUVEC were respectively incubated with alone Cap (10μM),paraoxon(3.63μM),HA,PO(3.63μM)plus Cap(0.1,1,10μM), PO(3.63μM)plus SOD,PO(3.63μM)plus CAT,PO(3.63μM)plus Ena, PO(3.63μM)plus Cap(10μM)and PHMB for 30 min.HUVEC monolayer permeability,endothelial cell activity,biochemical index in the cell cultured fluid and morphology of the endothelial cell were examined.RESULTS:(1)Paraoxon(0.00363～36.3μM)concentration and time-dependently inhibited ACh-induced EDR,but did not affect SNP-induced endothelium-independent relaxation of aortic isolated rings. PO resulted in a reduction of both SOD activity and nitrite oxide(NO) content and increase of the malondialdehyde(MDA)content in the vascular tissue.Cap(0.1～10μM)concentration-dependently lessened the inhibition of ACh-induced EDR injured by PO,but did not affect SNP-induced endothelium-independent relaxation of aortic rings.The preincubation Cap(10μM)obviously lessened the inhibition of AChinduced EDR and protected against reduction of both SOD activity and NO content and increase of the MDA content in the vascular tissue induced by PO(3.63μM).PO(0.00363～36.3μM)concentration and time-dependently resulted in an increase of permeability of the endothelial monolayer and reduction of energy in cultured HUVEC.PO induced morphology changes of endothelial cell which included a trachychromatic cellular nucleus and enlarged cell spaces.PO also resulted in a reduction of both SOD activity and NO content and increase of the MDA content in the cell cultured fluid.Cap(0.1～10μM) concentration-dependently lessened the increase of permeability of the endothelial monolayer induced by PO.The Cap(10μM)obviously lessioned the increase of vascular endothelial cell monolayer permeability and protected against reduction of energy and both SOD activity and NO content in cultured HUVEC as well as increase of the MDA content in the cell cultured fluid induced by PO.SOD and CAT have the analogic function as the Cap to protect the endothelial cell from being injured by PO.Ena can not protect the vascular endothelial cells from being injured by PO,the effects of Cap could inhibited by PHMB,a sulfhydryl group blocking agent.CONCLUSION:PO could directly injure the function of vascular endothelium in vitro and increase the endothelial cell monolayer permeability.The mechanisms of PO-induced vascular endothelial injures may related to the oxidation stress-mediated reduction of NO release and formation of lipid peroxidation induced by PO.The sulfhydryl(SH)-containing ACE inhibitors Cap can protect the vascular endothelium from being injured by PO and the mechanism may relate to nonenzymatic antioxidant defenses.