Transepithelial resistance, measurement

Transepithelial electrical resistance (TEER) measurements and transport smdies implied that CS/y-PGA NPs can be effective as an insulin carrier only in a limited area of the intestinal lumen where the pH values are close to the p/iTa of chitosan. So, a pH-responsive nanoparticle system was self-assembled by TMC and y-PGA for oral delivery of insulin. In contrast, TMC(40% Degree of Quatemisation) / y-PGA NPs may be a suitable carrier for transmucosal delivery of insulin within the entire intestinal tract. The loading efficiency and loading content of insulin in TMC/ y-PGA NPs were 73.8 2.9% and 23.5 2.1%, respectively. TMC/y-PGA NPs had superior stability in a broader pH range to CS/y-PGA NPs the in vitro release profiles of insulin from both test nanoparticles were significantly affected by their stability at distinct pH environments. TEER experiments showed that TMC/y-PGA NPs were able to open the tight junctions between Caco-2 cells, and this was further confirmed by confocal microscopy [66]. 

Cell cultures. MDCK cells were seeded in the Transwells at a density of 2.2 x 104 cells/cm. Cells were fed by changing medium in both upper (apical) and lower (basal) compartments periodically. Confluent monolayers were obtained at 5-7 days post-inoculation, when the cell density reached 4.5-5.0 x 105 cells/cm2, and a transepithelial electrical resistance (TEER) of about 2,000 ohms cm2 was measured using an epithelial voltohmmeter (EVOM, World Precision Instruments, West Haven, CT). The amount of FBS in the cell culture medium could be decreased as the cells approached their maximum resistance, and could be maintained at that point for 2 days or longer in medium containing 1% FBS. 

The in vitro system we have been using to study the transepithelial transport is cultured Madin-Darby canine kidney (MDCK) epithelial cells (11). When cultured on microporous polycarbonate filters (Transwell, Costar, Cambridge, MA), MDCK cells will develop into monolayers mimicking the mucosal epithelium (11). When these cells reach confluence, tight junctions will be established between the cells, and free diffusion of solutes across the cell monolayer will be markedly inhibited. Tight junction formation can be monitored by measuring the transepithelial electrical resistance (TEER) across the cell monolayers. In Figure 1, MDCK cells were seeded at 2 X 104 cells per well in Transwells (0.4 p pore size) as described previously. TEER and 14C-sucrose transport were measured daily. To determine 14C-sucrose... 

Evaluation of the epithelial integrity can be performed by measuring the transepithelial electrical resistance (TEER). TEER values ranging from 150 ohms.cm2 up to 600 ohms.cm2 have been reported. An alternative method for assessing the monolayer integrity is to monitor the flux of hydrophilic marker molecules that pass the monolayers by the paracellular route (e.g., mannitol, Na-fluorescein, or atenolol). 

Most studies of the local actions of opioids on the intestinal mucosa have utilized muscle-stripped sheets of ileal mucosa with attached submucosa mounted in Ussing flux chambers. Peptidase-resistant enkephalin derivatives such as DPDPE decrease short-circuit current, an electrical measure of active transepithelial ion transport, across isolated mucosal sheets from the guinea pig ileum [46,127,128], rabbit ileum [129-131], mouse jejunum [132], and pig distal jejunum/ileum [133]. This effect, which occurs after the application of opioid agonists to the serosal aspect of epithelial sheets, is due to an increase in electroneutral salt absorption and a decrease in electrogenic chloride secretion [46,132,133], In contrast to enkephalin derivatives, opiate alkaloids have limited effects on active transepithelial transport of ions [69]. Pretreat-... 

Control measurements of the monolayer include measurements of transepithelial resistance with an Endohm Meter (World Precision Instruments, New Haven) and permeability measurements of mannitol and polyethylenglycol 4000 (marker for low... 

Integrity control of the monolayer is based on measurements of both TEER (transepithelial resistance measurements) and permeability for a standard marker (radioactive mannitol or Lucifer yellow as non-radioactive alternative). 

Sutton, S.C. Forbes, A.E. Cargill, R. Hochman, J.H. LeCluyse, E.L. Simultaneous in vitro measurement of intestinal tissue permeability and transepithelial electrical-resistance (teer) using sweetana grass diffusion cells. Pharm. Res. 1992, 9, 316-319. 

The transepithelial electrical resistance measures predominantly the permeability of tight junctions for small ionic solutes. A partial disruption of tight junctions would not be detected by changes in permeability but by a drop in transepithelial resistance, which is reflected by an asymptotic relationship of... 

This buffer is used in both the unidirectional (permeability) and the bidirectional (Efflux, Section 4.3.2). In the permeability assay, NCEs are placed into the apical compartment of the Transwell. Duplicate samples are taken immediately after compound addition from the apical compartment (zero time) and then after 2h from both the apical and basolateral compartments for LC-MS/MS analysis. The integrity of the monolayer is confirmed by the measurement of the transepithelial electrical resistance (TEER), which must be above a certain limit to be used for transport experiments. In addition, with each experiment a transcellular and a paracellular marker are included for quality control. 

The tight junction has also been implicated in the regulation of the transepithelial salt flux across proximal tubule. Measurements in Necturus proximal tubule have shown that when the animal is in a volume expanded state there can be a 3-fold decline in epithelial resistance due essentially to a change in the paracellular shunt resistance [61], In the volume expanded state then, although active transport of salt into the lateral interspace is little changed from the control conditions, enhanced backflux of salt across the tight junction into the lumen results in substantially diminished transepithelial salt flux [61-63]. These increases in junctional permeability are likely mediated by increases in peritubular (serosal) and hence, lateral interspace pressure [64,65]. 

In particular barrier systems such as the blood-brain barrier (BBB) are characterized by the so-called transepithelial electrical resistance (TEER). The TEER is considered an important measure of function and quality of tight junctions which are formed between endothelial cells making up the barrier. CThanges in TEER may indicate leakage due to toxic side effects of drugs or may be a desired effect of a drug that is to pass the BBB in order to treat a disease within the central nervous system. Also, TEER is routinely measured to establish proper function of a barrier system (BBB, gut) prior to the tests of drug permeability. 

X 10 cells/filter) 4-5 days before. Measure the transepithelial resistance (TER) of each filter before use (different cell lines have different TER values, you should use the monolayer at plateau values of TER). 

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