More information and illustrations about the structure and function of the glycocalyx and tight junctions are available online from an academic textbook called, Molecular Cell Biology, 4th Ed.:
- Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000. Section 15.7, Transport across Epithelia. Available from: http://www.ncbi.nlm.nih.gov/books/NBK21502/.
Interestingly, cells grown in a solution with very low concentrations of calcium ions formed a monolayer with a lack of tight junctions between the cells but when calcium ions were added to the solution, tight junctions formed between the cells within an hour.
–This could suggest that calcium ions are necessary for cell monolayers to be able to form the tight junctions — or it might suggest that tight junctions are formed between cells in the presence of calcium in order to prevent the calcium ions from passing between the cells. Or in other words: Does the presence of calcium ions allow the tight junctions to form? Or do the tight junctions form because there are calcium ions present that need to be prevented from passing through the cell monolayer?
More research has been done and it suggests that the intracellular calcium ion level is also important for maintaining strong tight junctions. Both intra- and extrcellular levels of calcium are kept under careful control during normal health. Tight junctions also will become disfunctional if intracellular calcium levels become elevated.
- Rachel C. Brown, PhD, Thomas P. Davis, PhD, Calcium Modulation of Adherens and Tight Junction Function; A Potential Mechanism for Blood-Brain Barrier Disruption After Stroke, Stroke, 2002; 33: 1706-1711 (full text) [http://stroke.ahajournals.org/content/33/6/1706.full]
- A one page glossary with illustrations that includes a brief description of different types of cell junctions and the glycocalyx: [http://biology.clc.uc.edu/fankhauser/Labs/Genetics_Cell/GENETICS_CELL_LECTURES/22_Cell_Junctions.Nov12.pdf]
Magnesium ions inside of the cell are also important for controlling intracellular levels of calcium. Nutrients usually have to work together as a team.
/Disclosure: This information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes./