Dashwood Michael R, Tsui Janice C S
Clinical Biochemistry, Royal Free and University College Medical School, Royal Free Campus, Pond Street, London NW3 2QG, UK.
Exp Biol Med (Maywood). 2006 Jun;231(6):802-5.
Elevated plasma and tissue endothelin (ET)-1 levels in patients with critical limb ischemia (CLI) has been described. Here the effect of a period of acute ischemia and subsequent reperfusion on plasma ET-1 and tissue ET-1/ET receptors in skeletal muscle biopsies from CLI patients undergoing femoro-distal bypass surgery was studied. Peripheral and "local" blood and muscle biopsies were obtained from patients undergoing femoro-distal bypass surgery, at the start of the procedure (control), after a period of vascular clamping (ischemia), and after clamp release (reperfusion). Plasma ET-1 was determined by enzyme-linked immunosorbent assay. Tissue ET-1 was assessed by counting ET-1 immunostaining cells per unit area, and ET(A)/ET(B) receptors were identified on sections by in vitro autoradiography in which binding was quantitatively assessed by densitometry. There was no significant effect of ischemia or reperfusion on plasma ET-1 levels or on ET(A)/ET(B) receptor binding. However, tissue ET-1 increased during both acute ischemia and reperfusion (P < 0.05). A high proportion of positive ET-1 immunostaining was associated with microvessels and also exhibited a similar distribution to macrophages. Previously, it has been shown that both plasma ET-1 and tissue ET-1/ET receptors are increased in CLI patients compared with atherosclerotic controls. Also, increased muscle ET-1 levels have been described in acute ischemia caused by tourniquet application in nonischemic patients undergoing total knee replacement. In CLI patients, in whom ET-1 is already upregulated, this further increase may exacerbate existing pathologic processes and contribute to ischemia-reperfusion injury. ET-1 antagonists may therefore be useful adjuncts in CLI and other surgical procedures in which ischemia-reperfusion damage occurs.
已有研究描述了严重肢体缺血（CLI）患者血浆和组织内皮素（ET）-1水平升高的情况。在此，我们研究了急性缺血期及随后的再灌注对接受股-远端旁路手术的CLI患者骨骼肌活检组织中血浆ET-1和组织ET-1/ET受体的影响。在手术开始时（对照）、血管钳夹一段时间后（缺血）以及钳夹松开后（再灌注），从接受股-远端旁路手术的患者获取外周血和“局部”血液以及肌肉活检样本。通过酶联免疫吸附测定法测定血浆ET-1。通过计算每单位面积的ET-1免疫染色细胞来评估组织ET-1，并通过体外放射自显影在切片上鉴定ET(A)/ET(B)受体，其中通过光密度测定法定量评估结合情况。缺血或再灌注对血浆ET-1水平或ET(A)/ET(B)受体结合均无显著影响。然而，在急性缺血期和再灌注期组织ET-1均升高（P < 0.05）。高比例的ET-1阳性免疫染色与微血管相关，并且在分布上也与巨噬细胞相似。此前研究表明，与动脉粥样硬化对照组相比，CLI患者的血浆ET-1和组织ET-1/ET受体均增加。此外，在接受全膝关节置换的非缺血患者中，已描述了因使用止血带导致急性缺血时肌肉ET-1水平升高。在ET-1已经上调的CLI患者中，这种进一步升高可能会加剧现有的病理过程并导致缺血-再灌注损伤。因此，ET-1拮抗剂可能是CLI及其他发生缺血-再灌注损伤的外科手术中的有用辅助药物。
