兔体外循环中糖皮质激素受体变化及应用大剂量糖皮质激素的效应

本文应用兔体外循环（ＣＰＢ）模型研究ＣＰＢ中糖皮质激素受体（ＧＲ）的变化及早期应用大剂量糖皮质激素（ＧＣ）的效应。结果发现，兔胸腺高亲和力ＧＲ数目在ＣＰＢ６０ｍｉｎ较ＣＰＢ前显著下降（－３５％），ＣＰＢ中血浆ＧＣ浓度显著升高，同时伴有血浆磷脂酶Ａ２（ＰＬＡ２）活性和肺血管外含水量（ＥＶＬＷ／ＢＦＤＬ）显著升高；在ＣＰＢ前５ｍｉｎ静注琥珀酸钠氢化考的松２０ｍｇ／ｋｇ，虽使胸腺ＧＲ水平进一步下降（－６９％），但能显著提高ＣＰＢ期间血浆ＧＣ浓度，并能显著抑制血浆ＰＬＡ２活性和ＥＶＬＷ／ＢＦＤＬ的升高。提示ＣＰＢ能引起ＧＲ水平下降，从而降低ＧＣ效应；ＣＰＢ术中早期应用大剂量ＧＣ能在ＣＰＢ中ＧＲ减少的情况下维持或提高ＧＣ的效应，但其作用很可能并非完全通过高亲和力ＧＲ介导。

Changes of glucocorticoid receptor and effects of early high-dose glucocorticoid application during cardiopulmonary bypass in rabbits

The changes of glucocorticoid receptor (GR) and effects of early high-dose glucocorticoid (GC) application during cardiopulmonary bypass (CPB) were studied on the CPB model in rabbit.The results showed that thymocytic GR of high affinity decreased markedly at 60 min and plasma GC concentrations rose significantly during CPB,the former decreased more markedly and the latter rose more significantly during CPB by given high-dose GC (hydrocortisone 20 mg/kg) 5 min before CPB.Plasma phospholipase A_2(PLA_2) activities and extravascular lung water/blood-free dry lung ratio increased significantly during CPB but both of them were greatly inhibited by high-dose GC used.These data suggested that the GC biological response is reduced due to the decrease of GR and may be maintained or enhenced during CPB by pretreatment with high-dose GC,and the effects of which is unlikely to be completely mediated by GR of high affinity.