MEASUREMENT OF β-ENDORPHIN IN HUMAN PLASMA

Abstract
β-endorphin has been identified in human plasma by means of gel filtration and a sensitive radioimmunoassay for human β-endorphin (βh-endorphin). Mean baseline plasma βh-endorphin concentration in 5 individuals was 21±7.3 (SD) pg/ml (6.2 ± 2.2 (SD) fmole/ml). Following metyrapone stimulation mean plasma concentration increased to 55.4 ± 10.1 (SD) pg/ml (16.3 ± 3.1 (SD) fmole/ml). The molar ratio of human 3-lipotropin (βh-LPH) to βh-endorphin was 2.2 in baseline plasma and 2.4 after metyrapone stimulation.