一氧化氮参与非诺贝特抗高糖高胰岛素诱导的心肌肥大

目的研究过氧化物酶体增殖物激活受体-α(peroxi-some proliferator-activated receptor-α,PPAR-α)特异性激动剂非诺贝特(fenofibrate,FF)在高糖高胰岛素(high glucose and insulin,HGI)所致心肌细胞肥大中的作用及其与一氧化氮(nitric oxide,NO)途径的关系。方法乳鼠心肌细胞培养,以细胞表面积、蛋白含量和心房利钠因子mRNA表达为心肌肥大反映指标,观察FF对HGI致肥大作用的影响。利用Real-time PCR和Western blot方法检测mRNA及蛋白水平的表达;比色法和硝酸还原法分别检测细胞培养液中一氧化氮合酶(nitric oxide synthase,NOS)的活性和NO的浓度。结果FF浓度依赖性地抑制HGI诱导的心肌细胞肥大(P<0.01);FF0.3μmol·L-1明显上调HGI导致的PPAR-α以及内皮型一氧化氮合酶(endothelial nitric oxide synthase,eNOS)mRNA和蛋白表达的降低(P<0.05);并增加HGI降低的NOS活性和NO浓度(P<0.01)。PPAR-α阻断剂MK886可完全取消FF的上述作用(P<0.05)。L-精氨酸的作用与FF相似(P<0.01)。结论FF可能通过激活PPAR-α,从而促进eNOS的表达及NO的释放,产生抗HGI诱导心肌肥大的作用。

NO pathway involves in the anti-hypertrophic effects of fenofibrate induced by high glucose and insulin

Aim To investigate the role of fenofibrate (FF),a selective PPAR-α agonist,in cardiac hypertrophy induced by high glucose and insulin (HGI) and its mechanisms related to nitric oxided (NO) signal transduction pathway. Methods The cultured neonatal rat cardiomyocytes were used to observe the effects of FF on cardiomyocyte hypertrophy induced by HGI (glucose at 25.5 mmol·L-1 and insulin at 0.1 μmol·L-1),and the cardiomyocyte hypertrophic responses were assayed by measuring the cell surface area,protein content,and atrial natriuretic factor (ANF) mRNA expression. The expressions of mRNA and protein were assayed by Real-time PCR and Western blot,as well as NOS activity and NO concentration in cultured media were determined by using the spectrophotometry and nitrate reluction method.Results In cultured cardiomyocytes,FF (at 0.1,0.3 and 1 μmol·L-1) could inhibit the cardiomyocyte hypertrophy induced by HGI in a concentration-dependent manner (P<0.01). FF at 0.3 μmol·L-1 significantly increased both mRNA and protein expressions of PPAR-α and endothelial nitric oxide synthase (eNOS) (P<0.05). At the same time,FF at 0.3 μmol·L-1 could also elevate nitric oxide synthase activity and NO concentration in cultured media (P<0.01). All of these effects of FF could be abolished by MK 886 (at 0.3 μmol·L-1),a selective PPAR-α antagonist (P<0.05).L-arginine had similar effects to FF (P<0.01). Conclusions FF attenuates cardiomyocyte hypertrophy induced by HGI,and the underlying mechanism may be involved in the elevation of the expression of PPAR-α,and the increase of the expression of eNOS and the release of NO.