腺苷对猪缺血再灌注心肌组织一氧化氮合酶同工酶的影响

Effect of adenosine on nitric oxide synthase isoenzyme in myocardium in a mini-swine model of ischemia and reperfusion

目的:评价缺血再灌注后一氧化氮合酶(NOS)同功酶的变化以及腺苷对其的影响。方法:中华小型猪24只,随机分成缺血再灌注模型组、腺苷组和假手术组,每组8只。冠状动脉结扎180min,松解60min制备缺血再灌注模型。检测缺血前5min,缺血后5,180min和再灌注后5,60min血NO的含量并观察正常、缺血和无再流区心肌组织内NOS同功酶及其mRNA的表达。结果:(1)与缺血前比较,缺血后180min、再灌注后5min和60min的血NO水平均显著降低(均P<0.01),然而再灌注后5min和60min的血NO水平比缺血后180min有显著升高(均P<0.01)。而腺苷组缺血后180min血NO降低幅度显著低于模型组(P<0.05)。再灌注后5min和60min的血NO水平与缺血后180min相比无显著变化(P>0.05)。(2)与正常区心肌组织相比较,模型组和腺苷组一样,缺血区和无再流区心肌组织中结构型一氧化氮合酶(cNOS)活性及其mRNA表达均显著减低,诱导型一氧化氮合酶(iNOS)活性及其mRNA表达均显著升高(均P<0.01),而无再流区cNOS活性及其mRNA表达减低和iNOS活性及其mRNA表达的升高比缺血区均更显著(P<0.05或P<0.01)。与模型组相比较,腺苷组仅缺血区心肌组织中iNOS活性及其mRNA表达显著降低,cNOS活性及其mRNA表达显著升高(P<0.05或P<0.01)。结论:NOS的变化可能是无再流发生的重要机制之一。腺苷可能通过升高cNOS活性,降低iNOS活性起到了减少无再流的作用。

AIM: To evaluate the effect of adenosine on nitric oxide synthase (NO S) isoenzyme after ischemia-reperfusion. METHODS: Twenty-four mini-swines wer e r andomly divided into control group, adenosine-treated group, and sham-operated g roup (n=8 in each group). The mini-swines were subjected to 180 min of coro nary arte ry occlusion followed by (60 min) of reperfusion. Serum nitric oxide (NO) leve l wa s measured at 5 min before ischemia, 5 and 180 min after ischemia, and 5 and 60 min after reperfusion. The activity and mRNA expression of constitutive NOS (cNO S) and inducible NOS (iNOS) in normal, ischemia, and no-reflow area of myocardi u m were also evaluated. RESULTS: (1) Compared with the baseline, serum NO level decreased at 180 min after ischemia as well as at 5 and 60 min after reperfusio n (a ll P<(0.01)). However serum NO level at 5 and 60 min after reperfusion was hig her than that at 180 min after ischemia. In adenosine-treated group, the decrease i n se r um NO level at 180 min after ischemia was lower than that in the control group ( P <0. 05). The serum NO level at 5 and 60 min after reperfusion was not significantly different compared with that at 180 min after ischemia. (2) Compared with norma l my ocardium, cNOS activity and mRNA expression decreased and (iNOS) activity and mRNA expression increased in both ischemia and no-reflow area of control and adenos i ne-treated group (all P<(0.01).) But the decrease in cNOS activity and mR NA e xpres sion and the increase in iNOS activity and mRNA expression was more significant in no-reflow area compared with those in ischemia area (P<0.05 or P<0.0 1). After adenosine pretreatment, iNOS activity and mRNA expression decreased and cNOS ac tivity and mRNA expression increased only in the ischemia area compared with con trol group (P<0.05 or P<0.01). CONCLUSION: The change of nitric oxide s ynthase could be one of the important mechanisms for no-reflow phenomenon. Adenosine co uld reduce no-reflow by increasing cNOS activity and decreasing iNOS activity.