Fang V S, Fessler R G, Rachlin J R, Brown F D
Clin Chem. 1984 Feb;30(2):311-4.
An effect of metrizamide, a contrast medium, on results of beta-endorphin radioimmunoassay was examined. We found that 1, 5, and 10 microL of the medium added to 100 microL of standard containing 0 to 500 pg of beta-endorphin shifted the standard curve to the left in proportion to the metrizamide concentration. Three other contrast media showed a similar effect at low concentrations of beta-endorphin. This effect of contrast media artificially increased results in radioimmunoassay of beta-endorphin in cerebrospinal fluid, the mean overestimate being 121.9% (range, 0 to 435%). For plasma samples, this effect of contrast media resulted in an average 11.7% overestimate of beta-endorphin (range, -16% to 41%). These observations bring into question the validity of a previous suggestion that an increase in beta-endorphin in cerebrospinal fluid after intracerebral electrical stimulation is the mechanism for stimulation-produced analgesia.
研究了造影剂甲泛葡胺对β-内啡肽放射免疫测定结果的影响。我们发现，向含有0至500 pgβ-内啡肽的100 μL标准品中加入1、5和10 μL该造影剂，标准曲线会随着甲泛葡胺浓度成比例地向左移动。其他三种造影剂在低浓度β-内啡肽时也显示出类似的效果。造影剂的这种作用人为地提高了脑脊液中β-内啡肽放射免疫测定的结果，平均高估121.9%（范围为0至435%）。对于血浆样本，造影剂的这种作用导致β-内啡肽平均高估11.7%（范围为-16%至41%）。这些观察结果对先前的一种观点提出了质疑，该观点认为脑内电刺激后脑脊液中β-内啡肽增加是刺激产生镇痛作用的机制。
