The influence of lectin concanavalin A on the configuration of renal podocytes.

Concanavalin A (ConA) was applied directly to renal glomerular podocytes by micropuncture techniques in vivo. Others received a control solution without ConA. To make visible the distribution of ConA, some rats were given fluorescein-isothiocyanate conjugated ConA. The glomeruli undergoing the micropuncture experiments were labeled and then prepared for SEM observation. Comparatively, the effect of application of the same solutions by intra-arterial infusion was studied. The glomeruli of a total of 33 Munich -rats were studied. Our results show that direct contact of ConA with the podocytes is needed to induce retraction of the podocytic cell processes. The pattern of podocytes treated with ConA is comparable to that of the minimal change nephrotic glomeruli. ConA seems to act by blocking anionic surface charges of the podocytes. This reduction in negative charges along the surface coat of the podocytes could be the key for understanding the combined morphological and functional alterations in podocytes of nephrotic glomeruli: The reduction in negative charges along the surface coat of the podocytes can alter the permselectivity for anionic and cationic proteins and can, at the same time, alter the configuration of the podocytes by changing the potential gradient along the cell membrane.