Glomerular mesangium: its function and relationship to angiotensin II.

The glomerular mesangium is composed of mesangial cells and an intercellular material, the mesangial matrix. Partly because of its unique anatomic location, the mesangium appears to be susceptible to immune- and non-immune-mediated injury. Mesangial cells have characteristics similar to smooth muscle cells, and their surface is covered with receptors that bind a variety of vasoactive substances. The glomerular mesangium seems to play an important role in the physiologic regulation of the glomerular microcirculation. There is evidence that a plasmic flow carrying macromolecules circulates through the mesangium. Changes in glomerular hemodynamic determinants and in the release and/or production of vasoactive substances, particularly angiotensin II, can greatly influence the mesangial movement of macromolecules. Quantitative and/or qualitative alterations in the mesangial movement of macromolecules may lead to mesangial injury.