Adipose tissue microdialysis

Adipose tissue poses additional calibration differences for microdialysis sampling devices. The thickness of the tissue (e.g., lean versus obese individuals) and thus the capillary density will affect interindividual microdialysis sampling recovery values. This has been shown by Lutgers et al., who demonstrated decreases in glucose recovery of up to 50% between human volunteers with a skin fold thickness of 20 versus 45 mm.65 This points to how microdialysis sampling recovery is dependent upon analyte supply since glucose will be supplied better to the microdialysis probe in lean individuals with a higher density of capillaries per unit tissue than obese subjects with a lower density of capillaries and thus an increased mass transfer resistance to the probe. Additional reports have also shown less interindividual differences between microdialysis probes implanted in the forearm versus in the subcutaneous tissue.66... 

Wientjes KJC, Grob U, Hattemer A, Hoogenberg K, Jungheim K, Kapitza C, Schoonen AJM. Effects of microdialysis catheter insertion into the subcutaneous adipose tissue assessed by the SCGM1 system. Diabetes Technology Therapeutics 2003,5,615-620. 

Wientjes KJ, Vonk P, Vonk-van KY, Schoonen AJ, Kossen NW. Microdialysis of glucose in subcutaneous adipose tissue up to 3 weeks in healthy volunteers. Diabetes Care 1998, 21, 1481-1488. 

Wientjes KJC, Hoogenberg K, Schoonen AJM. Transport of glucose to aprobe in adipose tissue. In Westerink, Cremers (Eds), Handbook of Microdialysis. Academic Press, 2007. 

LutgersHL, HullegieLM, Hoogenberg K, SluiterWJ, DullaartRPF, Wientjes KJ, Schoonen AJM. Microdialysis measurement of glucose in subcutaneous adipose tissue up to three weeks in type 1 diabetic patients. Netherlands Journal of Medicine 2000, 57, 7-12. 

Gustafsson J, Eriksson J, Marcus C. Glucose metabolism in human adipose tissue studied by 13C-glucose and microdialysis. Scandinavian Journal of Clinical and Laboratory Investigation 2007, 67, 155-164. 

Arner P, Bolinder J. Microdialysis of adipose tissue. Journal of Internal Medicine 1991, 230, 381-386. 

Schoonen AJM, Wientjes KJ. A model for transport of glucose in adipose tissue to a microdialysis probe. Diabetes Technology Therapeutics 2003, 5, 589-598. 

Figure 6.4 The starting setup for the clinical use of microdialysis in human adipose tissue consists of a portable, battery-driven syringe micropump (CMA 106) and a flexible microdialysis catheter (CMA 60). The catheter (A) is introduced into the tissue by means of a special introducer (B). The needle has a longitudinal channel opening on its side, which allows its removal from the tissue and disconnection from the microdialysis catheter. The sample is collected into a special microvial (C).

For this application, a sterile microdialysis catheter is implanted percutane-ously into the subcutaneous adipose tissue in the periumbilical region using a special stainless steel guide cannula (Rosdahl et al., 1993). The membrane length of 2 to 3 cm and flow rates of 0.1 to 0.5 piL/min should guarantee sufficiently long dialysis time to achieve 100% recovery. Another approach is to use a flat dialysis probe for transcutaneous applications (DeBoer et al., 1993 Korf et al., 1993). Here the skin of newborn babies is first partially removed by stripping with medical tape. Then a microdialysis probe is placed directly onto the exposed skin, usually on the abdomen lateral to the umbilicus (DeBoer et al., 1994). 

Bolinder J, Hagstrom E, Ungerstedt U, Arner P (1989) Microdialysis of subcutaneous adipose tissue in vivo for continuous glucose monitoring in man. Scand J Clin Lab Invest 49 465-474. 

Bolinder J, Ungerstedt U, Arner P (1992) Microdialysis measurement of the absolute glucose concentration in subcutaneous adipose tissue allowing glucose monitoring in diabetic patients. Diabetologia 35 1177-1180. 

Rosdahl H, Ungerstedt U, Jorfeldt L, Henriksson J (1993) Interstitial glucose and lactate balance in human skeletal muscle and adipose tissue studied by microdialysis. J Physiol London 471 637-657. 

Lourido J, Ederoth P, Sundvall N, Ungerstedt U, and Nordstrom CH (2002) Correlation between blood glucose concentration and glucose concentration in subcutaneous adipose tissue evaluated with microdialysis during intensive care. Scandinavian Journal of Clinical and Laboratory Investigation 62 285-292. 

Microdialysis is used to collect solutes present in the extracellular fluid via a microdialysis probe with a semipermeable membrane at its tip (see Fig. 14.8). The probe is perfused by a buffer (perfusate), and solutes from the environment surrounding the probe diffuse though the membrane into the perfused solution. Perfusate with the solutes (dialysate) is then collected for ex situ analysis. Microdialysis has been used in vivo to monitor the local concentrations of solutes in the extracellular fluids in a number of different tissues. The first microdialysis experiments were conducted on the brain and blood plasma (Bito et al., 1966). It has since been used to study metabolism in numerous tissues such as brain, muscles, tendons, subcutaneous adipose tissue, lungs, kidneys, and liver (Flock and Kloft, 2005 de la Pena et al., 2000 Jackson, 2005 Siddiqui and Shuaib, 2001). Microdialysis is widely used for pharmacokinetic research (Davies, 1999 de Lange et al., 2000 Verbeeck, 2000) and has also been used to monitor cell metabolites in cell culture medium (Wu et al., 2001). 

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