The T84 human colonic epithelial cell line retains the ability to produce secretagogue-responsive monolayer cultures with high transepithelial resistance when grown and maintained on collagen-coated permeable supports in media supplemented with 5% newborn calf serum. The addition of highly purified insulin to the basolateral but not the apical membrane side of established monolayers caused the transepithelial resistance to decline more than eightfold over a 3-4-d period. By comparing the transepithelial flux of 22Na with that of the extracellular space marker, [3H]mannitol, the decline in electrical resistance was shown to be due solely to an effect on tight junction-mediated paracellular permeability. The effect of insulin was dose dependent with a half-maximal effect at 3.9 ng/ml (approximately 0.7 nM) and fully reversible over a 10-d time course. Simultaneous addition of 2 microM cycloheximide prevented the insulin-induced decline in resistance; in fact, this combination caused a significant increase in electrical resistance. There was no effect on the short-circuit current response of insulin-treated monolayers to secretagogues so long as media was changed daily. While no gross morphological changes were apparent, there did appear to be a subtle condensation of the perijunctional actin ring as visualized using rhodamine-labeled phalloidin. These results demonstrate that insulin modulates the permeability of the occluding junction in T84 cell monolayers through a receptor mediated process which probably involves changes in protein synthesis and cytoskeletal structure. Insulin was also shown to produce similar effects on two other intestinal epithelial cell lines.
J A McRoberts, R Aranda, N Riley, H Kang
Usage data is cumulative from May 2023 through May 2024.
Usage | JCI | PMC |
---|---|---|
Text version | 67 | 0 |
37 | 20 | |
Figure | 0 | 2 |
Scanned page | 48 | 0 |
Citation downloads | 10 | 0 |
Totals | 162 | 22 |
Total Views | 184 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.