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Angiotensin II enhances the endocytosis of proteins by podocytes in vivo ő a multiphoton microscopy study (1173.1)
Author(s) -
Schiessl Ina Maria,
Castrop Hayo
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1173.1
Subject(s) - endocytosis , glomerulus , chemistry , losartan , alexa fluor , renal glomerulus , kidney glomerulus , angiotensin ii , vesicle , podocyte , in vivo , microbiology and biotechnology , endocrinology , kidney , receptor , glomerulonephritis , biochemistry , membrane , proteinuria , biology , physics , quantum mechanics , fluorescence
Glomerular filtration may trap plasma proteins within the filtration barrier. We assessed the hypothesis that podocytes clear these proteins by endocytosis. Experiments were performed in young Munich Wister Froemter rats using intravital multiphoton microscopy. Rhodamin B was injected i.v. to label plasma proteins. To assess the regulation of the endocytotic activity of podocytes, z‐stacks of glomeruli were acquired, and the volume of the dye‐containing vesicles within the podocytes was determined. At baseline, the total volume of Rhodamin B‐containing vesicles in podocytes averaged 5.8±3.2 µm 3 /glomerulus and remained stable over time. During the infusion of Ang II (80 ng/kg/min), podocytes rapidly accumulated Rhodamin B‐labeled proteins, and the volume of dye‐containing vesicles increased to 193±32 µm 3 /glomerulus (p=.001). This was blocked by the AT1 antagonist losartan (9.9 mg/kg). Similar results were obtained for Alexa 584‐labeled albumin. The endocytosis of the low molecular weight Texas Red dextrane (10 kDa) by podocytes also increased during the infusion of Ang II (from 240±47 to 394±55 µm 3 /glomerulus; p=.003), while the glomerular sieving coefficient of TxR dextrane remained unchanged. In summary, our data provide evidence that podocytes have endocytotic activity in vivo. The endocytosis is enhanced by Ang II, and this is only partially related to changes in the macromolecule filtration.