外源性H_2S恢复老龄大鼠心肌缺血后适应对I/R损伤的缓解作用

Exogenous H_2S restores ischemic postconditioning-induced protection against I/R injury in heart of aging rats

目的探讨外源性硫化氢(H_2S)恢复缺血后适应(PC)对老龄大鼠心肌的保护作用及相关机制。方法将青年和老龄大鼠随机分别分为对照组、缺血/再灌注(I/R)组和PC组,老龄大鼠另加Na HS干预组。用Langendorff离体灌流装置,复制大鼠心肌I/R损伤和PC模型。比色法测定冠脉流出液LDH、CK活性和心肌组织匀浆SOD活性、MDA含量及H_2S产率;透射电镜检测心肌超微结构;TTC染色测定心肌梗死面积;TUNEL染色检测心肌细胞凋亡;Western blot检测caspase-3、caspase-9、Bcl-2及胱硫醚-γ-裂解酶(CSE)的表达。结果无论青年还是老龄大鼠,与对照组比较,I/R降低H_2S产率、SOD活性和CSE表达,增加LDH和CK活性、MDA含量、心肌损伤、细胞凋亡、心肌梗死面积、caspase-3、caspase-9及Bcl-2的表达(P<0.01);与I/R组比较,青年大鼠的PC减轻I/R损伤及细胞凋亡(P<0.01),而老龄大鼠的PC丧失了对心肌的保护作用;外源性H_2S恢复了老龄大鼠的PC对I/R损伤的保护作用。结论外源性H_2S能够恢复老龄大鼠PC对心肌的保护作用,其机制与抗氧化、清除自由基、抑制细胞凋亡有关。

Objective To explore the myocardial protective effects and possible mechanisms of hydrogen sulfide （ H2 S） in the recovery of ischemic post-conditioning （PC） in the aging rats. Methods Wistar young and aging rats were randomly divided into control group, ischemia/reperfusion （I/R） group, ischemic post-conditioning （PC） group. In addition, aging rats were treated with Naris （PC ＋ NariS）. The model of myocardial I/R injury and PC in isolated rats hearts was induced with Langendorff system ; LDH, CK activities of coronary effluent and SOD activ- ity and MDA content as well as H2 S production rate of myocardial tissue homogenate were measured by colorimetric method; Myocardial ultrastructure was detected by transmission electron microscope ; The myocardial infarct size was measured by Trc staining; Myocardial cell apoptosis was detected by TUNEL staining; The expression of Bcl-2,caspase-3 and caspase-9 was detected by Western blot. Results I/R decreased H2S production rate, SOD activity and CSE expression, increased LDH and CK activity, MDA content, myocardial injury, apoptosis, myocardial infarct size, caspase-3 and caspase-9 and Bcl-2 expression（P 〈0.01 ）; PC reduced I/R injury and apoptosis in the young hearts （ P 〈 0.01 ） , however, PC lost myocardial protective effect in the aging hearts; Exogenous H2S restored the PC-induced cardioprotection in aging hearts. Conclusions Our results suggest that exogenous H2S restores the myocardial protective effect of PC via anti-oxidation, scavenging free radical and inhibiting apoptosis.