| Objective: To approach the localization of podocin in glomerulus and its posssible role in proteinuria occuring in nephropathic syndrome as well as the effect of prednisone and benazepril on its density in glomerulus so as to study the possible mechanism of prednisone and benazepril in treating NS. Methods: 40 young SD rats ( 1- month- old ,weighing around 150g)were chosen in this experiment,32 rats as the nephropathic group were injected with adriamycin(5mg/kg) via tail-vein for one time,and the other 8 rats as the normal-control group were injected with 0.9% saline.Two weeks after the injection ,the excretion of 24 hrs urinary protein of all rats was detected and those with 24 hrs urinary protein >30mg were chosen as nephropathic rats .All nephropathic rats were further randomly divided into 3 groups: nephropathy-control group(n=8),prednisone-treated group(n=8),benazepril-treated group(n=8). Prednisone-treated rats and benazepril-treated rats were administrated with prednisone 10mg/(kg. d) and benazepril 3mg/(kg. d) respectively , the normal-control rats and nephropathy-control rats were administrated with 0.9% saline.Four weeks later urinary protein were measured, and meanwhile all rats were killed and their renal cortex were taken for localization and semi-quantitive analysis of podocin Results 1. podocin was distributed at the base of the podocyte foot processes near the GBM. It was primarily located at the cytoplasmic face of the plasma membrane adjacent to the filtration slits. Small clusters of particles of podocin were occasionally found along the surface of the foot processes at a distance from the GBM. No significant labelling was observed on the GBM or the podocyte cell bodies.No labelling was detected on Bowman's capsules,endothelialor mesangial cells.2 .At the end of the experiment,we gain optical density (A)of each group through Metaphorgh as following: normal-control group: 0.298 0.0414; nephropathy-control group:: 0.562 0.0375; prednisone-treated group : 0.406 0.0261 ;benazepril-treated group: 0.427+0.0323 .Compared with the nephropathy-control group,optical desnsity was significantly different (F= 77.56, P<0.001).The staining intensity of podocin decreased prominently in nephropathic samples compared with normal-control group while the staining intensity of podocin increased in prednisone-treated and benazepril-treated samples compared with untreated nephropathic samples.Conclusions: Podocin is a major component of the slit diaphram;the concentration of podocin decreased prominently in nephropathic samples; it is possible that prednisone and benazepril reduce the excretion of urine protein by affecting the intensity of podocin in the glomerulus .
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