Hashizume T, Nitta Y, Kasuya K, Kanematsu S
Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Iwate University, Morioka, Japan.
Domest Anim Endocrinol. 1995 Oct;12(4):363-70. doi: 10.1016/0739-7240(95)00049-k.
A microdialysis sampling technique for the intracerebral measurement of somatostatin (SS) in extracellular fluid was examined in the goat. The microdialysis probe (70-mm shaft, 0.5 mm outer diameter) contained at its tip a 4-mm length of copolymer dialysis membrane (20 kDa cut-off). Artificial cerebrospinal fluid (artificial CSF) was pumped through the probe tip at a rate of 4 microliters/min with a batter-driven syringe pump, and effluent fractions of dialysate (120 microliters) were collected every 30 min. An in vitro recovery test showed that changes in the SS concentration in dialysate were highly correlated (r = 0.95, P < 0.01) with those in the external medium, and the relative recovery averaged 2.0%. As a validation for in vivo microdialysis, trails were conducted with conscious behaving goats wherein the inflow dialysate was changed transiently from artificial CSF with low potassium (2.5 mM) to a solution of 300 mM KCl. Potassium-induced depolarization around the probe tip located in the preoptic area and in the hypothalamus induced an increase in SS concentrations in dialysate at each location. In the most remarkable response, the concentrations of SS were increased 6-fold and 11-fold in the first and second 30-min fractions, respectively, compared with prepotassium concentrations. These results suggest that intracerebral SS levels in extracellular fluid could be estimated from conscious behaving goats by the use of our intracerebral microdialysis system.
在山羊身上研究了一种用于脑内测量细胞外液中生长抑素（SS）的微透析采样技术。微透析探针（杆长70毫米，外径0.5毫米）尖端包含一段4毫米长的共聚物透析膜（截留分子量20 kDa）。用电池驱动的注射泵以4微升/分钟的流速将人工脑脊液（人工CSF）泵入探针尖端，每30分钟收集一次120微升的透析液流出部分。体外回收率测试表明，透析液中SS浓度的变化与外部介质中的变化高度相关（r = 0.95，P < 0.01），相对回收率平均为2.0%。作为体内微透析的验证，对清醒活动的山羊进行了实验，其中流入的透析液从低钾（2.5 mM）的人工CSF短暂更换为300 mM KCl溶液。位于视前区和下丘脑的探针尖端周围由钾诱导的去极化导致每个位置透析液中SS浓度增加。在最显著的反应中，与钾前浓度相比，SS浓度在第一个和第二个30分钟部分分别增加了6倍和11倍。这些结果表明，通过使用我们的脑内微透析系统，可以从清醒活动的山羊身上估计细胞外液中的脑内SS水平。
