^(99)Tc^m-PnAO-硝基咪唑和^(99)Tc^m-HL91对乏氧心肌的实验研究

An experimental study of 99 Tc m PnAO nitroimidazole and 99 Tc m HL91 in detection of myocardial hypoxia

目的探讨９９ＴｃｍＰｎＡＯ硝基咪唑和９９ＴｃｍＨＬ９１２种乏氧心肌显像剂用于实验性心肌缺血、缺氧的作用。方法进行小鼠体内分布与离体大鼠心脏模型研究，以９５％Ｏ２和５％ＣＯ２平衡的ＫｒｅｂｓＨｅｎｓｅｌｅｉｔ缓冲液进行主动脉逆行灌注为对照组；以Ｎ２取代Ｏ２和ＣＯ２平衡的ＫｒｅｂｓＨｅｎｓｅｌｅｉｔ缓冲液进行逆行灌注为乏氧组；以９５％Ｏ２和５％ＣＯ２平衡的ＫｅｒｂｓＨｅｎｓｅｌｅｉｔ缓冲液低流量（ｌｍＬ／ｍｉｎ）逆行灌注，为低流组；以停止灌注２０ｍｉｎ再恢复灌注为缺血再灌注组。所有离体心脏在经过含示踪剂的缓冲液灌注２０ｍｉｎ后，再以不含示踪剂的缓冲液持续灌注６０ｍｉｎ。用γ相机动态采集心脏图像，测量心脏放射性。结果①２种示踪剂摄取最高的脏器是肝脏和肾脏，肝／心比值在注射９９ＴｃｍＰｎＡＯ硝基咪唑３０ｍｉｎ和６０ｍｉｎ后分别为１１６和６９，注射９９ＴｃｍＨＬ９１３Ｏｍｉｎ和６０ｍｉｎ后分别为５７和６．２。②和对照组比较，乏氧心肌、低流灌注心肌和缺血再灌注心肌９９ＴｃｍＰｎＡＯ硝基咪唑的滞留量均显著增高，６０ｍｉｎ时与对照组心肌滞留量的比值分别为４８、３７和２．８。乏氧心肌９９Ｔｃｍ?

Objective To investigate the biological characteristics of two hypoxic avid imaging agents, 99 Tc m PnAO nitroimidazole and 99 Tc m HL91, and the experimental myocardial hypoxia, low perfusion and ischemic reperfusion were performed Methods Isolated rat hearts were retrogradely perfused with Kerbs Henscleit buffer (KH) in four phantoms: control, low perfusion, ischemic reperfusion and hypoxia Control hearts were perfused with 95% O 2 and 5% CO 2 balanced KH at 9～10 mL/min rate Low perfusion hearts were perfused with the same KH at 1 mL/min rate, and ischemic reperfusion rat hearts were discontinued perfusion for 20 min then reperfused with the same KH Hypoxic hearts were perfused with 100% N 2 balanced KH Results ①At 30 and 60 min, the radioactivity ratio of liver to heart (L/H) was 11 6 and 6 9 ( 99 Tc m PnAO nitroimidazole), and 5 7 and 6 2 ( 99 Tc m HL91), respectively The lung to heart ratios at 60 min of 99 Tc m PnAO nitroimidazole and 99 Tc m HL91 were 1 8 and 2 1, respectively ②The accumulation of 99 Tc m PnAO nitroimidazole in the hypoxic, low perfusion and ischemic hearts was 4 8, 3 7 and 2 8 times that in the control hearts At 60 min after starting washout, the retentions of 99 Tc m PnAO nitroimidazole in hypoxic, low flow and ischemic reperfusion myocardium were much higher than that of control hearts [(23 7±9 1)%] The accumulation of 99 Tc m HL91 in the hypoxic and low perfusion hearts was also significantly higher than that in the control and ischemic reperfusion hearts, P<0 01 However, there was no significant difference between control and ischemic reperfusion hearts After 60 min's washout, the retention of 99 Tc m HL91 in the low perfusion heart was 5 34, 3 43 and 1 23 times those of control, ischemic reperfusion and hypoxic hearts, respectively Conclusions 99 Tc m PnAO nitroimidazole can be accumulated in low perfusion, ischemic reperfusion and hypoxic hearts, while 99 [KG*2/3]Tc m HL91 is mainly accumulated in hypoxic, specially low perfusion hearts Since there is a high L/H in perfusions with either agent, the detecting of inferioposterior wall may be impacted while using them as imaging agents