title: Time Delay of Microdialysis in vitro.
abstract: BACKGROUND
  Microdialysis is a specific and local sampling method to collect free molecules from the extracellular fluid, however, there are no reports on time delay issues of microdialysis applications.
  
  
  OBJECTIVE
  This study was to check the time gap between the start of target molecule changes in detected fluid and corresponding stable concentration formation in the sampled dialysate.
  
  
  METHODS
  A designated microdialysis system for free calcium ion was set up in vitro and perfused with saline. The dialysate was diluted synchronously, and collected in a vial every 10 min. The free calcium concentration [Ca++] of the sample was measured by an atomic absorption spectrophotometer. A signal-switching method was introduced to mimic the target molecule [Ca++] changes in the detected fluid, standard calcium solution and saline.
  
  
  RESULTS
  There was a notable lag in dialysates [Ca++] for both uprising and down going course in spite of instant switching between the detected fluids. The recovery time (RT) of the microdialysis system was extrapolated to be 20 min for [Ca++] detection.
  
  
  CONCLUSIONS
  With 10 min sampling interval, [Ca++] time delay of the microdialysis system existed, and could not be estimated precisely beforehand. The signal-switching method was applicable for RT calibration in vitro with a dedicated microdialysis system.
authors: Department of Cardiothoracic Surgery, Third Affiliated Hospital, Guangzhou, China.
authors: Shao-Hong
authors: SH
authors: Huang
authors: Jian
authors: J
authors: Zhang
authors: Yun
authors: Y
authors: Li
authors: Jian
authors: J
authors: Rong
authors: Zhong-Kai
authors: ZK
authors: Wu
keywords: Calcium; Microdialysis; Time delay
references: Skin Pharmacol Physiol. 2010;23(5):225-43
references: 20484965
references: Trends Biotechnol. 2010 Mar;28(3):150-8
references: 20079945
references: J Clin Pharmacol. 2007 May;47(5):589-603
references: 17442685
references: J Pharmacol Toxicol Methods. 2000 Nov-Dec;44(3):519-25
references: 11395330
references: Clin Chim Acta. 2002 Apr;318(1-2):121-5
references: 11880121
references: J Am Coll Nutr. 2004 Oct;23(5):561S-565S
references: 15466966
references: Cardiovasc Res. 2008 Mar 1;77(4):782-90
references: 18056767
references: Pharm Res. 1997 Mar;14(3):267-88
references: 9098867
references: J Diabetes Sci Technol. 2009 Sep 01;3(5):1207-14
references: 20144438
references: Electrophoresis. 2010 Jan;31(1):55-64
references: 20039293