A cytochemical study of gl.ycocalyx and the membrane cholesterol of rat glomerular podocytes.

Abstract

Summary. In order to elucidate the cytochemical properties of rat podocyte's membranes, the authors studied the constituents and distribution of glycocalyx and membrane cholesterol. Chromic -phosphotungstic acid (Cr-PTA) stain combined with enzyme digestive tests was used for the glycocalyx analysis. A digitonin fixation method was applied for the detection of membrane cholesterol.On the whole surface of podocytes, glycocalyx showed a strongly positive reaction to Cr-PTA. In normal rats, the reactivity on the urinary surface above the slit membrane of the podocyte foot processes was decreased after treatments with neuraminidase, hyaluronidase and heparitinase. The reactivity on the basal surface below the slit membrane disappeared only after treatment with chondroitinase ABC. In Puromycin Aminonucleoside nephrosis (PAN) rats, the foot processes were effaced extensively. Though a highly positive reactivity of Cr-PTA was observed on the urinary surface of the podocytes, the basal surface reacted weakly. The positive reaction of the urinary surface was not affected by the treatments with neuraminidase, hyaluronidase and heparitinase, but the weak reaction of the basal surface disappeared completely through chondroitinase ABC treatment. The distribution of membrane cholesterol was clearly revealed by the digitonin fixation method, showing digitonin cholesterol complexes of localized trilamellar structures. In normal rat podocytes the complexes were found on the urinary surface, with only a few on the basal surface. In PAN rats the complexes were seldom noticed either on the urinary or basal surfaces. The heterogeneous distribution of glycocalyx and membrane cholesterol seen in normal rat podocytes are changed remarkably under nephrotic condition.

Glomerular filtration into the subpodocyte space is highly restricted under physiological perfusion conditions

“…Previous studies have shown that there is a substantial glycocalyx on the urinary side of the GBM, overlying the podocytes (7,8,14). In an examination of published information on cryofixed glomeruli showing preservation of a podocyte glycocalyx, the glycocalyx was ϳ70 nm high, extending away from the podocyte plasma membrane (5,10,17,18) and coats both the lower and upper surfaces of what appears to be the subpodocyte space, cell body, and foot processes.…”

Vascular Endothelial Glycocalyx Damage and Potential Targeted Therapy in COVID-19

“…Glycocalyx is defined as a complex gel-like layer of glycosylated lipid–protein mixtures, which surround all living cells and serves as a buffer between cells and the extracellular matrix (ECM) [ 25 , 33 , 34 ]. The glycocalyx layer is uniform in leucocytes, neurons, fibrocytes, and other cells of mesenchymal origin, whereas it appears thicker at apical than at lateral and basal membranes in epithelial cells [ 34 , 35 ]. Endothelial glycocalyx layer (EGL) is synthesized and secreted by vascular ECs and extends along the endothelial layer covering the luminal surface of blood vessels [ 36 ].…”

Gangliosides in Podocyte Biology and Disease

“…Cholesterol was early revealed as a key component of podocyte membrane. Initially found in normal rat podocytes as especially present in the urinary side and less abundantly in the basal side [9], it was shown as a key component of the slit diaphragm through its interaction with podocin [10], one of the resident proteins in this raft-like structure [11].…”