Development of microdialysis probe for the kidney

被称为微透析的“生物采样”技术最初是由Ungerstedt及其同事开发的。该方法的原理是从细胞外液（ECF）中提取代谢物，而不从组织中去除液体。基本装置是一个薄的（直径0.65毫米）双腔探针，尖端有半透性聚碳酸酯膜。用等渗盐水灌注探针。小分子沿着灌注液和ECF之间的浓度梯度通过简单的扩散穿过探针膜。采用高效液相色谱等灵敏分析技术测定透析液微样中各种代谢产物的含量。因此，微透析可以用于各种代谢物ECF含量的区域变化的时间研究。这种方法最初是为研究脑组织而设计的。然而，微透析探头的直径为0.65 mm。对于高血流速率灌注的肾脏来说，这个尺寸相对较大。此外，由于肾脏的运动与呼吸是同步的，因此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，对探针的透析效率要求很高。因此，为了满足上述几点，我们尝试开发一种新的肾脏微透析探针。新型探针的直径仅为0.2 mm，透析效率是商用探针的5 - 10倍。利用这种新开发的探针，我们研究了缺血和再循环过程中肾内腺苷的代谢。基础条件下腺苷浓度（conc.）在100 nM左右。缺血使腺苷含量升高。大约2次。然而，在EHNA抑制腺苷脱氨酶后，腺苷会被抑制。缺血时增加50 - 100倍以上。另一方面，腺苷连接。碘结核菌素抑制腺苷激酶后仅增加3 ~ 4倍。因此，腺苷从ce中释放出来

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 with a seim-permeable polycarbonate membrane at the tip. The probe is perfused with an isotonic saline. Small molecules cross the probe membrane by simple difusion along a concetration gradient between the perfusate and the ECF.The dialysate microsample content of various metabolizes is measured by sensitive analytical techniques including HPLC.Thus, microdialysis can be used for temporal studies of regional changes in the ECF content of various metabolizes. The method was originally designed for studies in brain tissue. However, the diameter of the microdialysis probe is 0.65 mm. This size is relatively large for the application to the kidney which is perfused at high blood flow rate. Moreover, since the kidney moves in synchronicity with the respiration, 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 examined the intrarenal adenosine metabolism during ischemia and recirculation. Adenosine concentration(conc.) at basal condition was around 100 nM.Ischemia increased the adenosine conc.about 2 times. However, after the inhibition of adenosine deaminase with EHNA the adenosine conc.was increased more than 50 - 100 times during ischemia. On the other hand, adenosine conc.after the inhibition of adenosine kinase with iodotubercidine increased only 3 - 4 times. Thus, the adenosine released from the ce