血液稀释下多培沙明多巴胺和多巴酚丁胺对外周血管阻力的影响

Effects of Dopexamine,Dopamine and Dobutamine on Peripheral Vascular Resistance following Acute Normovolemic Hemodilution in Rats

为观察血液稀释下多培沙明（ＤＰＸ）、多巴胺（ＤＯＰ）和多巴酚丁胺（ＤＯＢ）对外周血管阻力的影响及前者的影响机制，将４８只大鼠随机分为Ｉａ、Ｉｂ、Ⅱ和Ⅲ四组（每组１２只）进行后肢恒流灌注，分别在血液稀释或阻断多巴胺受体２（ＤＡ２）及β受体（Ｉｂ组）前后注药，记录后肢灌注压（ＰＰ）的变化。结果显示：Ｉａ组ＤＰＸ３、１０、３０μｇ／ｋｇ使ＰＰ下降２０％、２０％和３２％（Ｐ＜０．０１），释稀后ＤＰＸ不改变ＰＰ；Ｉｂ组ＤＡ２阻断后，ＰＰ升高２３％（Ｐ＜０．０１），注入ＤＰＸ使其下降（Ｐ＜０．０５）；β受体阻断后ＰＰ升高３４％（Ｐ＜０．０１），ＤＰＸ仍使ＰＰ明显增高（Ｐ＜０．０１）；Ⅱ组ＤＯＰ小剂量ＰＰ无变化，大于１０μｇ／ｋｇ使ＰＰ增加２３％（Ｐ＜０．０５），稀释后ＤＯＰ使ＰＰ更明显升高（Ｐ＜０．０１）；Ⅲ，ＤＯＢ１、３和１０μｇ／ｋｇ使ＰＰ下降１３％、２０％和３７％（Ｐ＜０．０１），但稀释后ＤＯＢ不改变ＰＰ。提示：血液稀释可减弱ＤＰＸ及ＤＯＢ对外周血管的舒缩效应；ＤＰＸ激动β２受体发挥其扩血管作用；大剂量ＤＯＰ有明显缩血管作用，血液稀释使其作用增强。

To investigate the effects of dopexamine(DPX),dopamine(DOP)and dobutamine(DOB)on peripheral vascular resistance (PR) following acute normovolemic hemodilution,fourty eight rat hindlimb perfused preparations were randomly divided into four groups(n=12 each group):group Ⅰ a given DPX 3,10,30μg/kg,group Ⅱ given DOP 1,3,10,30μg/kg; group Ⅲ given DOB 1,3,10μg/kg;DPX, DOP and DOB were administered before and after hemodilution(Hct to 20%) resulted from blood withdrawal(25ml/kg) and replacement of an equal volume of 6% dextran(mean molecular weight is 7000,000)in 5% glucose and in normal saline,and group Ⅰ b.given DPX 3,10,30μg/kg after selective dopamine receptor 2(DA 2) blockade with haloperidol or β receptors blockade with propranolol.The changes of hindlimb perfusion pressure(PP)were continuously measured to evaluate the responses of PVR to DPX,DOP and DOB.The results:DPX at the dose of 3,10 and 30 μg/kg caused a dosedependent decreases in PP but no changes following hemodilution;After selective DA 2 blockade which resulted in increase of 23% in PP,DPX still caused PP decrease,but DPX increased PP significantly(P<0 01) after β receptors blockade;DOP at the dose of 1 and 3μg/kg had no effect on PP,while DOP at the dose of 10 and 30 μg/kg produced 12% and 23% increases in PP,respectively and more increase(P<0 01) after hemodilution;DOB at the dose of 1,3,10μg/kg resulted in a dose dependent decrease in PP but no change following hemodilution.It is concluded that the vasoactivities of DPX and DOB can be attenuated and vasoconstriction of DOP be potentiated following hemodilution,and that DPX produces vasodilation effect through stimulating β 2 adrenergic receptor.