钙离子体外微渗透的时间延迟

目的检验微渗透（MD）系统回收时间（RT）延迟的存在性。方法建立一个用于钙离子（ca2＋）检测的特定MD体外系统。灌注液为生理盐水（NS），灌注速度为2．0μl／min。析出液经过同步稀释，每10分钟采样1次至80min。样本中的Ca2＋用原子吸收光谱仪检测，计算MD系统的Ca2＋回收率。用Ns和Ca2＋标准液间的切换模拟待测液目标分子浓度变化，记录不同时间点的ca。’浓度和MD系统用于caz＋检测的RT。结果MD系统的ca。’回收率为16％，析出液钙离子浓度自10min[（57±17）μmol／L]开始上升，20min达到峰值，持续至50min[（159＋26）Ixmol／L]开始下降，稳态峰值浓度约200I~mol／L。基线值时间点组（0、60、70、80min）与峰值时间点组（20、30、40min）间Ca2’浓度差异有统计学意义[0min：（3＋4）μmol／L，60min：（7±8）μmo]／L，70min：（7＋7）μmol／L，80min：（5＋9）μmol／L比20min：（197±29）μmol／L，30min：（194＋21）μmol／L，40min：（192＋11）μmol／L，均P〈0．05]。析出液中ca2＋浓度上升和下降变化均较待测液显著延迟，对于该MD系统而言，用于caz＋检测的RT应为20min。结论在10min的采样间隔下，MD系统的caz＋检测RT延迟存在，并且不能事先准确预估。信号切换方法用于RT延迟的校正是可行的。

Time lag of calcium ion microdialysis in vitro

Objective To ascertain the existence of recovery time （RT） lag during microdialysis （MD） in vitro. Methods A specialized MD system for in vitro detection of free calcium ion was constructed. Perfusion was conducted by using normal saline （NS） at a rate of 2.0 μl/min. The dialysate was diluted synchronously and collected in a vial at 10- minute intervals for 8 times. The free calcium concentration （ [ Ca2＋ ] ） in the sample was measured by atomic absorption spectrophotometer for computation of the retrieval rate of MD system. Signal-switching between standard calcium solution and NS was employed to mimic changes in [Ca2＋] in the target solution. This was followed by recording of [Ca2＋] and RT regarding detection of [Ca2＋ ] via MD system. Results A recovery rate of 16% for MD system was revealed. The [Ca2＋ ] increased at 10 min [ （57＋ 17）μ mol/L], peaked during steady-state at 20 rain （200 μ mol/L） and was well- maintained till 50 mint （159±26） μ mol/L） ] followed by a subsequent reduction. An overall difference（all P〈 O.05）in [Ca2＋] between peak time points[20, 30 and 40 min, for 20 min： （197±29）μmol/L, 30 min. （194± 21 ） μ mol/L, 40 min ： （ 192± 11 ） μ mol/L ] and baseline time points [ 0, 60, 70 and 80 min, for 0 minute ： （3± 4）p.mol/L, 60 rain： （7±8）μmol/L, 70 rain： （7e7）txmol/L, 80 rain： （5±9）μ mol/L]was noted. The increase and decrease in [ Ca2＋ ] in the dialysate showed a noticeable time lag as compared with the target solution. An RT of 20 minutes corresponded to measurement of [ Ca2＋ ] by using the MD system. Conclusion The time lag for the MD system to detect [Ca2＋] is measurable at lO-minute intervals. This should not warrant precise estimation prior to the measurement. The signal-switching technique proves applicable for RT calibration.