High and low affinity binding sites for endothelin on cultured rat glomerular mesangial cells |
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Authors: | K F Badr K A Munger M Sugiura R M Snajdar M Schwartzberg T Inagami |
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Institution: | Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-2372. |
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Abstract: | Endothelin contracts glomerular mesangial cells, thereby influencing glomerular size and filtration rate. Here, we demonstrate the presence of two ET-specific binding sites on cultured rat mesangial cells with Kds of 0.76 and 44.70 nM, and maximal binding capacity (Bmax) values of 6.78 x 10(2) and 27.60 x 10(2) binding sites/cell, respectively. Binding of 125I]-ET was maximal at 120 min at 4 degrees C, stable for the subsequent 60 min, and selective. No competition for binding was observed with greater than 1000-fold concentrations of atrial natriuretic peptide, angiotensin II, arginine vasopressin, nicardipine, or nifedipine. The presence of specific receptors for ET on glomerular mesangial cells suggests a major role for this peptide in the regulation of glomerular filtration rate. |
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