Mesangial function and glomerular sclerosis in rats after unilateral nephrectomy.

To investigate the possible relationship between disturbance of mesangial function and segmental localization of glomerular sclerosis, five uninephrectomized male Wistar rats and five sham-operated controls received colloidal carbon intravenously. At 4 months 8.4 +/- 2.5% of the glomeruli of the nephrectomized rats showed focal sclerosis. Glomeruli of nephrectomized rats contained significantly more carbon than glomeruli of controls. Glomeruli with focal sclerosis contained significantly more carbon than normal glomeruli in the same kidneys with a preferential tracer localization within the lesions. In another experiment carbon injections were given before surgery. At 4 months 12.6 +/- 4.1% of the glomeruli of the nephrectomized rats showed focal sclerosis, an incidence not significantly different from that of the first experiment. Glomerular carbon content was equal in experimental and control rats and no preferential localization of the tracer within the lesions was found. From these results we conclude that the preferential localization of carbon in the glomerular lesions in rats nephrectomized before injection of carbon is caused by the increased delivery of tracer shortly after injection to those glomerular areas where sclerosis will develop at a later time. The development of focal sclerosis may be related to the local deposition of harmful substances from the circulation.