MEASUREMENT OF IMMUNOREACTIVE γ-MSH IN HUMAN PLASMA |
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| Authors: | ANN C. HALE SALLY J. RATTER SUSAN J. TOMLIN N. LYTRAS G. M. BESSER LESLEY H. REES |
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| Affiliation: | Departments of Chemical Endocrinology and Endocrinology, St. Bartholomew's Hospital, London, EC1A 7BE |
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| Abstract: | A radioimmunoassay for immunoreactive γ-MSH (IR-γ-MSH) in human plasma has been developed. The assay is capable of detecting normal basal circulating levels which range from < 20-100 ng/1 at 0900 h. Plasma levels are raised concomitantly with ACTH during insulin induced hypoglycaemia and CRF stimulation and suppressed with dexamethasone. Chromatographic characterisation of IR-γ-MSH in plasma demonstrates a major peak of IR-γ-MSH, corresponding to purified glycosylated N-terminal pro-opiome-lanocortin 1-76, when IR-γ-MSH is secreted from the pituitary. In contrast IR-γ-MSH produced ectopically appears to be heterogeneous. |
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