Permeability of Basement Membranes to Macromolecules

Abstract

Conclusions

Basement membranes are important structures within many tissues, and for at least some tissues, the ability of the basement membranes to restrict the passage of macromolecules is important for function. We have concentrated on the renal glomerular and tubular basement membranes because they have been studied more than others, but the basement membranes of capillaries may be important in many different organs (65). In the renal glomerulus, the GBM certainly plays an important role in restricting the passage of serum proteins into the forming urine; however, some data are conflicting, and the relative roles of cells and the GBM are not yet defined. In the renal proximal tubule, the TBM may play a part in the process of epithelial transport of fluid, and the example that we have given shows the importance of considering the dynamics of the in vivo situation in assessing the role of the basement membrane. Describing the permeability properties of basement membrane will require more work in vitro, and investigators need to be aware of the possible artifacts induced by isolation procedures.

The author is an Established Investigator of the American Heart Association. Research work mentioned here was funded by National Institutes of Health Grant DK39023 and by grants from the American Diabetes Association Indiana Affiliate and the Juvenile Diabetes Foundation International. The author thanks Judy Boyd-White, George Tanner, Jeff Siemon, and Andrew Evan for helpful critique of the manuscript.