Changes of anionic sites in the mesangium with aging in rats: a comparison of the immersion and intravenous PEI methods.

We investigated the changes in anionic sites of the mesangial matrix related to aging in rats, employing polyethyleneimine (PEI) as a cationic probe. We compared the numbers of anionic sites detected by the immersion method and by the intravenous administration of PEI. Analysis of the mean numbers of PEI particles per 0.1 micron2 in the mesangial matrix revealed a significant decrease related to aging. Our results suggested that there was no significant difference in efficacy between the immersion and intravenous methods. Loss of negative charge of the mesangial matrix is believed to promote mesangial dysfunction and the entrapment of macromolecular substances, and so to play an important role in the onset of glomerular sclerosis.