血管内皮舒张因子是否一氧化氮的探讨

Studies on whether Vascular Endothelium-derived Relaxing Factor is Nitric Oxide

血管内皮舒张因子(Endothelium-derived relaxing factor, EDRF)是血管内皮细胞产生释放的活性物质,它介导和决定许多舒血管活性物产生的舒张效应。已知硝基类扩血管药硝普钠(Sodium Nitroprusside,SNP)是通过形成一氧化氮(Nitric oxide, NO)而导致血管平滑肌产生舒张。有报导认为EDRF等同于NO。本文采用供受者双标本微量生物测定法,以SNP作为NO的供给源,通过比较EDRF与SNP舒张大鼠主动脉平滑肌的效应及其相互作用,以研究EDRF是否NO。结果发现:大鼠主动脉的内皮细胞在无活性物刺激时也能持续产生释放一种EDRF,即基础释放的EDRF(basal EDRF)。它可抑制NO的舒张效应,而NO作用于血管平滑肌后则可增强Ach激发的EDRF的舒张效应。可见,basal EDRF与NO的性质不相同,而激发的EDRF与NO的性质相似,EDRF与NO不能等同。为目前国际上这一争议提出了新的见解。

Endothelium-derived relaxing factor (EDRF) is a highly labile humoral agent released by vascular endothelium and plays an obligatory role in mediating the relaxation induced by vasodilators such as acetylcholine, bradykinin etc.It has been incceasingly notad that EDRF has physiological and pathophy-siolgical relevances in modulating vasomotor rssponses, but its chemical identity still remains to be resolved. Recently EDRF has bsen suggested to be identical to nitric oxide (NO) which is the chemical component responsible for endothe-lium-independent vasodilation produced by the nitrogen oxide contaning vasodilators such as sodium nitroprusside (SNP) etc. The present study is aimed to test whether EDRF is really NO. The vasorelaxing effects of EDRF and SNP which being as the source of NO were compared and the interaction between them were investigated by means of donor-recipient microbioassay in which the intact endothelium rat aortic strip as the donor and the denuded one as recipient. The results showed that EDRF not only could be elicited by vasoactive substances such as acetylcholine etc, but also could be continuously released in the resting state, which is called the basal EDRF. Basal EDRF inhibited the vasorelaxing effect of NO, whereas pretreatment with NO could significantly augment the relaxing effect of Ach-elicited EDRF in the recipient. In conclusion: 1 ) At least two EDRFs may be released from endothelium of rat aorta, a basal EDRF and an elicited one such as Ach-elicited EDRF. 2 ) According to the interaction mode between EDRF and NO, basal EDRF might differ fiom NO, and Ach-elicited EDRF might be similar to NO in nature.