Ryder S W, Eng J
J Clin Endocrinol Metab. 1981 Feb;52(2):367-9. doi: 10.1210/jcem-52-2-367.
Fasting human plasma immunoreactive leu-enkephalin (ir-leu-enkephalin) measured by radioimmunoassay averages 54+/-10 pg/ml. The method depends on acidification of plasma to protect against destruction of the peptide, adsorption to XAD-2 resin, extraction from the resin by aqueous methanol and concentration by evaporation. Plasma enkephalin in the dog increased from 13 to 56 pg/ml following insulin-induced hypoglycemia.
通过放射免疫分析法测定的禁食人类血浆免疫反应性亮氨酸脑啡肽（ir-亮氨酸脑啡肽）平均为54±10 pg/ml。该方法依赖于将血浆酸化以防止肽被破坏，吸附到XAD-2树脂上，用甲醇水溶液从树脂中提取并通过蒸发浓缩。胰岛素诱导的低血糖后，犬血浆脑啡肽从13 pg/ml增加到56 pg/ml。
