title: Impact of static pressure on transmembrane fluid exchange in high molecular weight cut off microdialysis.
abstract: With the interest of studying larger biomolecules by microdialysis (MD), this sampling technique has reached into the ultrafiltration region of fluid exchange, where fluid recovery (FR) has a strong dependence on pressure. Hence in this study, we focus on the fluid exchange across the high molecular weight cut off MD membrane under the influence of the static pressure in the sampling environment. A theoretical model is presented for MD with such membranes, where FR has a linear dependence upon the static pressure of the sample. Transmembrane (TM) osmotic pressure difference and MD perfusion rate decide how fast FR increases with increased static pressure. A test chamber for in vitro MD under static pressure was constructed and validated. It can hold four MD probes under controlled pressurized conditions. Comparison showed good agreement between experiment and theory. Moreover, test results showed that the fluid recovery of the test chamber MD can be set accurately via the chamber pressure, which is controlled by sample injection into the chamber at precise rate. This in vitro system is designed for modelling in vivo MD in cerebrospinal fluid and studies with biological samples in this system may be good models for in vivo MD.
authors.affiliation: Department of Engineering Sciences, Uppsala University, Box 534, 751 21, Uppsala, Sweden.
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Chu
authors.forename: Klas
authors.initials: K
authors.lastname: Hjort
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Dahlin
mesh_terms: D002555:Cerebrospinal Fluid / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D017551:Microdialysis / Q000379:methods*; D008956:Models, Chemical; D011312:Pressure