Detection of immunoreactive endothelin in plasma of hemodialysis patients |
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| Authors: | K Totsune T Mouri K Takahashi M Ohneda M Sone T Saito K Yoshinaga |
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| Institution: | Second Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan. |
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| Abstract: | Two types of radioimmunoassay (RIA) methods for measuring endothelin (ET) in human plasma were developed. One was an extraction procedure using a Sep-Pak C18 cartridge, the other being a direct method. By the extraction method, plasma ET levels were lower than the detectable limit (7 pg/ml) in normal subjects and elevated in hemodialysis patients. The absolute values obtained via the direct method were 20-times higher than those from extraction. Gel-filtration experiments revealed that this discrepancy was mainly due to immunoreactive (IR-) endothelin-like substances of high molecular mass near 11.6 kDa (large IR-ET). Extraction of the peptide by the C18 cartridge could eliminate interference by large IR-ET and is important in the accurate measurement of ET concentrations in plasma. |
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