PubMed · 10778148
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M Shichiri, Y Hirata. 1999. [Endothelin].. https://pubmed.ncbi.nlm.nih.gov/10778148/
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Recently it was suggested that abnormal endothelial function may contribute to the pathophysiological changes observed in preeclampsia (PE). Both nitric oxide (NO) and endothelin-1 (ET-1) are vasoactive substances produced by endothelial cells. NO is a vasodilator and has been believed to be decreased in PE. ET-1 is a vasoconstrictor and has been reported to be increased in PE. We simultaneously measured NO metabolites and ET-1 in sera from women with PE and investigated the correlation of NO and ET-1 concentrations. We obtained serum samples from 11 healthy nonpregnant (NP) women, 16 normotensive pregnant (NTP) women and 17 women with PE. In this study, the serum ET-1 level was assayed by the ET-1 RIA system, and serum NO metabolites were assayed by measuring nitrite (NO2-) and nitrate (NO3-) simultaneously in an HPLC-Griess reaction system. There was a significant correlation between NOx (nitrite + nitrate) and ET-1 in sera from all 44 women (NP, NTP and PE groups) (p<0.001). Nitrite and ET- in sera from each group were not significantly correlated. Nitrate and ET-1 in sera from the NP and NTP groups did not significantly correlate. However, there was a significant correlation between nitrate and ET-1 in sera from the PE group (p<0.05). The serum ET-1 and nitrate concentration in the PE group was significantly higher than in the NP and NTP groups (p<0.05 and p<0.001. respectively). These findings suggest that increased production of nitrate in PE may contribute to homeostatic vasodilation against vasoconstriction caused by a higher ET-1 concentration.
The possible diagnostic or prognostic significance of changes in circulating level of endothelins in a variety of pathological conditions is currently of interest. Unfortunately, no consensus regarding optimization of sensitivity and extraction procedures for the reliable radioimmunoassay of endothelin-1 (ET-1), big endothelin-1 (BigET-1), and endothelin-3 (ET-3) currently exists. The object of the present study was to evaluate aspects of currently used extraction and assay procedures that limit accurate determination of ET in human plasma and define criteria to reduce variability. Critical parameters include the selectivity of commercial antibodies and the ability to remove interfering material after Sep-Pak absorption by selective washing with 24% ethanol in 4% acetic acid or methylene chloride in 0.1% trifluoroacetic acid. Assay sensitivity and specificity in the physiological range is improved by optimizing total binding parameters for the antibodies to give approximately 15-20% binding of radiolabeled peptide. With these modifications normal plasma values for ET-1, BigET-1, and ET-3 averaged 1.7 +/- 0.06, 2.5 +/- 0.3, and 5.8 +/- 0.2 pg/ml, respectively. These data suggest that such modifications may help to resolve many of the earlier difficulties concerning the role of ET under normal and pathological conditions.
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