Their blood was sampled, and cryostat sections for the immunofluorescence study and total RNA for RT-PCR were prepared as described previously
Their blood was sampled, and cryostat sections for the immunofluorescence study and total RNA for RT-PCR were prepared as described previously.22,23 The amount of Monooctyl succinate urinary protein excretion/day was decided as described above. subtypes play reverse functions in regulating the barrier function of glomerular capillary wall and that the enhancement of AT2R Rabbit polyclonal to Sca1 activation may serve as a potential therapeutic strategy for proteinuria. Angiotensin II (Ang II) plays an essential role in maintenance of the vascular homeostasis and of several cellular and tissue functions in the physiological state. It is also understood that an excessive Ang II action contributes to the pathogenesis Monooctyl succinate of hypertension, heart failure, renal diseases, and several other diseases. Ang II action is explained as being based on blood pressure-dependent and -impartial mechanisms. Some recent studies focused on the significance of the pressure-independent mechanism of Ang II action.1,2 However, the tissue-specific function of local Ang II is not well understood. Although some reports3,4,5,6 have suggested that Ang II type 1 receptor (AT1R) and type 2 receptor (AT2R) exhibit opposite functions, this is still controversial. A number of clinical7,8,9,10 and experimental11,12,13,14,15 studies have exhibited that angiotensin-converting enzyme inhibitor and AT1R antagonist reduce renal tissue damage and proteinuria. However, their pharmacological mechanism is not well comprehended. In the nephrology field, clarification of the mechanism of proteinuria is one of the most important themes. Filtration barrier of the kidney glomerulus preventing the leak of plasma proteins into main urine comprises three layers16: the endothelial cells, the glomerular basement membrane, and the visceral epithelial cells (podocytes). Even though function of the glomerular basement membrane has been emphasized during the past 3 decades, it is recently becoming accepted that slit diaphragm located between adjacent foot processes of podocytes functions as the final barrier of the glomerular capillary wall.17 Recent studies show that this Monooctyl succinate dysfunction of the slit diaphragm is involved in the development of proteinuria in several common diseases such as minimal change type nephrotic syndrome and membranous nephropathy.18 Investigations of the role of Ang II action in regulating the barrier function of the slit diaphragm will surely lead to understanding better the mechanism of proteinuria. In the present study, we first analyzed the expression of AT1R and AT2R in anti-nephrin antibody (ANA)-induced nephropathy of which proteinuria was caused by down-regulation of the slit diaphragm functional molecules. Then, we investigated the effect of the AT1R antagonist on proteinuria in this model. We demonstrate that both AT1R and AT2R were expressed around the podocyte and that their expressions were clearly elevated in the proteinuric state. We show that this AT1R antagonist ameliorates the peak level of proteinuria by preventing a reduction in the expression of slit diaphragm functional molecules. In this study, we also investigated the selective functions of AT1R- and AT2R-mediated actions and experiments were performed using specific pathogen-free female Brown Norway rats weighing 100 to 110 g at the age of 7 to 8 weeks. All rats used in this study were purchased from Charles River Japan (Atsugi, Japan) and fed with normal salt diet. All animal experiments conformed Monooctyl succinate to the National Institutes of Health Guideline for the Care and Use of Laboratory Animals. Cultivation of conditionally immortalized mouse podocytes kindly donated by Dr. P. Mundel (Albert Einstein College of Medicine, Bronx, NY) was conducted as reported previously.19 The differentiated cells showing the prominent processes and mRNA expression of the differentiated molecules nephrin and podocin were utilized for the experiments. Experimental Protocols Experimental protocols for studies are shown in Physique 1. Open in a separate window Physique 1 Experimental protocols of studies. In experiment 1, rats were intravenously injected with ANA, and the kidneys were removed just before the injection and 1 hour and 24 hours and 3, 5, 8, 11, and 15 days after the injection. In experiment 2, rats were injected with ANA and treated with AT1R antagonist, hydralazine, or AT2R antagonist, and the kidneys were assessed on days 5 and 15. In experiment 3, rats were constantly injected with Ang II or AT2R agonist by osmotic pump, and kidneys were assessed at 24 and 72 hours. Experiment 1 To analyze the kinetics of podocyte-associated molecules and Ang II receptors, a total of 40 rats were intravenously injected with 10 mg of anti-nephrin monoclonal antibody prepared as explained previously,20 and five rats each were sacrificed just before the injection and at 1 and 24 hours, and 3, 5, 8, 11, and 15 days after the injection. The control group consisted of five rats, which were injected with 10 mg of irrelevant IgG1 (RVG1; mouse anti-rotavirus IgG1) and were sacrificed 15 days after the injection. After blood sampling, the kidneys were removed, weighed, slice into.