Development of microdialysis probe for the kidney and the heart

这种名为微透析的“生物采样”技术最初是由昂格斯泰特和他的同事开发的。这种方法的原理是从细胞外液(ECF)中提取代谢产物，而不从组织中去除液体。基本装置是一个薄的(0.65 mm直径)双腔探头。然而，对于以高血流速度灌流的肾脏或心脏来说，这个大小相对较大。此外，由于这些器官是移动的，所以探针的固定是困难的。此外，为了观察对各种刺激的快速反应，探头需要有较高的透析效率。因此，为了满足上述要求，我们尝试开发了一种新型的肾脏微透析探头。新型探头直径仅0.2 mm，透析效率是市售探头的5-10倍。利用这一新研制的探头，我们进行了以下实验。1)肾内腺苷(ADO)代谢：ADO浓度(conc.)在ba…再灌注条件约为200 nM。缺血使ADO浓度增加约3倍。然而，在用ehna抑制ADO脱氨酶后，ADO Conc.在缺血期间增加了50倍以上。而用碘代除草剂抑制ADO后，ADO浓度仅增加5倍。因此，肾缺血时细胞内产生的腺苷可能主要由ADO脱氨酶代谢，而ADO的再磷酸化可能较少。2)氟烷(Hal)对肾脏一氧化氮(NO)代谢的影响：吸入2%Hal可降低血压，降低肾间质cGMP(CGMP)和NOx浓度，吸入Hal同时给予硝普钠(NP)可使cGMP升高。提示Hal抑制肾脏一氧化氮-鸟苷环化酶信号通路，其部分机制可能是通过抑制Hal引起的肾脏血流动力学反应而实现的。此外，可以假设Hal的作用部位可能位于一氧化氮-鸟苷环化酶信号通路的近端。因此，新研制的微渗析探头是研究ECF中各种物质动力学的有用工具。较少

The "bio-sampling" technique called microdialysis was originally developed by Ungerstedt and colleagues. The principle of this method is to extract metabolizes from the extracellular fluid (ECF) without removal of fluid from the tissue. The basic device is a thin (0.65 mm diameter) double lumen probe. However, this size is relatively large for the application to the kidney or heart which is perfused at high blood flow rate. Moreover, since these organs move, the fixation of probe is difficult. In addition, to observe the rapid responses to various stimuli high dialysis efficiency will be required for probe. Thus, in order to satisfy the above points, we have tried to develop a new microdialysis probe for the kidney. The diameter of the new probe is only 0.2 mm and the dialysis efficiency is 5-10 times greater than the commercial probe. Using this newly developed probe we have performed the following experiments. 1) Intrarenal adenosine (Ado) metabolism : Ado concentration (conc.) at ba … More sal condition was around 200 nM.Ischemia increased the ado conc.about 3 times. However, after the inhibition of ado deaminase with EHNA the ado conc. was increased more than 50 times during ischemia. On the other hand, ado conc.after the inhibition of ado kinase with iodotubercidine increased only 5 times. Thus, the adenosine produced in the cell during renal ischemia might be mainly metabolized by ado deaminase and the rephosphorylation of ado might be small. 2) Effects of halothane (Hal) on the metabolism of nitric oxide (NO) in the kidney : Inhalation of Hal (2%) decreased blood pressure and the renal interstitial conc.of cyclic GMP (cGMP) and NOx, Administration of nitroprusside (NP) under the inhalation of Hal increased cGMP.These findings suggested that Hal inhibited the nitric oxide-guanylate cyclase signaling pathway in the kidney, and the renal hemodynamic responses to Hal might be induced, in part, through this inhibition. In addition, it can be assumed that the action site of Hal might be proximal to the nitric oxide-guanylate cyclase signaling pathway. Thus, the newly developed microdialysis probe is a useful tool for studying the dynamics of various substances in ECF. Less