Intrarenal Localization of Receptors for α-Rat Atrial Natriuretic Polypeptide: An Autoradiographic Study with [125I]-Labeled Ligand Injected in Vivo into the Rat Aorta

Kriz

Kretzler

2003

Physiological Reviews

1,307

1,278

Glomerular podocytes are highly specialized cells with a complex cytoarchitecture. Their most prominent features are interdigitated foot processes with filtration slits in between. These are bridged by the slit diaphragm, which plays a major role in establishing the selective permeability of the glomerular filtration barrier. Injury to podocytes leads to proteinuria, a hallmark of most glomerular diseases. New technical approaches have led to a considerable increase in our understanding of podocyte biology including protein inventory, composition and arrangement of the cytoskeleton, receptor equipment, and signaling pathways involved in the control of ultrafiltration. Moreover, disturbances of podocyte architecture resulting in the retraction of foot processes and proteinuria appear to be a common theme in the progression of acquired glomerular disease. In hereditary nephrotic syndromes identified over the last 2 years, all mutated gene products were localized in podocytes. This review integrates our recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier.

Section: A Cgmp Signalingmentioning

confidence: 99%

Cell Biology of the Glomerular Podocyte

Kriz

Kretzler

2003

Physiological Reviews

1,307

1,278

“…The depolarizing effect of hormones was mimicked by a Ca 2ϩ ionophore, suggesting that the Cl Ϫ conductance is activated by the release of Ca 2ϩ from intracellular stores Huber et al, 1998). Podocytes possess ANP receptors which are known to activate cellular cGMP (Koseki et al, 1986;Ardaillou et al, 1992). However, neither ANP nor the cell-permeable cGMP analog N2,2-o-dibutyryl-cGMP affected membrane voltage of podocytes in situ or in vitro, suggesting that, in contrast to mesangial cells, podocytes do not possess a cGMP activated ion conductance Cermak et al, 1996;Pavenstä dt, unpubl.…”

Section: Regulation Of the CLmentioning

confidence: 99%

Podocyte electrophysiology, in vivo and in vitro

Microscopy Res & Technique

Bek

2002

Podocytes are the most differentiated cell types in the glomerulus, which have been assumed to participate in the regulation of the ultrafiltration coefficient K(f). In podocytes in vivo and in vitro vasoactive agonists, such as angiotensin II and acetylcholine, increase the free cytosolic Ca(2+) concentration via a release of Ca(2+) from intracellular stores and an influx of Ca(2+) from the extracellular space. An increase of the cytosolic Ca(2+) in podocytes activates Cl(-) channels in podocytes in vivo and in vitro, resulting in a depolarization of podocytes. In vitro studies have shown that in addition to Ca(2+)-activated Cl(-) channels, cAMP-activated Cl(-) channels and Ca(2+)-activated K(+) channels are present in cultured podocytes. The characterization of the signaling pathways that regulate ion channels in podocytes may be important in the understanding of the regulation of the ultrafiltration coefficient K(f). This review summarizes the currently known electrophysiological properties of podocytes.

“…Rat podocytes in vivo possess ␣-atrial natriuretic peptide (ANP) receptors (33) and an increase of cGMP concentrations in human podocytes is induced by ANP (4,10). Infusion of ANP in adult or neonatal rats increases the cGMP level in podocytes, with a higher threshold for activation in immature animals, suggesting that the regulation of cGMP may play a role in podocyte development (11).…”

Section: Cellular Signaling and Hormones In Podocytesmentioning

confidence: 99%

Roles of the podocyte in glomerular function

American Journal of Physiology-Renal Physiology

2000

117

The podocyte is the most differentiated cell type in the glomerulum, which forms a crucial component of the glomerular filtration barrier. It has been assumed that podocyte foot processes counteract the elastic force of the glomerular basement membrane and that vasoactive hormones may regulate the contractile state of their foot processes and thereby modulate the ultrafiltration coefficient K(f). Podocyte damage leads to proteinuria, and podocyte injury occurs in many glomerular diseases, which may progress to chronic renal failure. The understanding of the regulation of physiological properties of the podocyte and the mechanisms of its cellular response to injury may thus provide a clue to the understanding of the pathogenesis of proteinuria and glomerular diseases. In the past it was difficult to study cellular functions in this cell type, because of its unique anatomic location and the difficulty in characterizing podocytes in cell culture. However, recent advances in physiological, molecular biological, and cell culture techniques have increased the knowledge of the role of the podocyte in glomerular function. The present review attempts to outline new aspects of podocyte function in the glomerulum.