Premium
ON THE STABILITY IN VITRO OF BIOACTIVE HUMAN ADRENOCORTICOTROPHIN IN BLOOD AND PLASMA
Author(s) -
LAMBERT A.,
FROST J.,
RATCLIFFE W. A.,
ROBERTSON W. R.
Publication year - 1985
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1985.tb00221.x
Subject(s) - endocrinology , medicine , radioimmunoassay , incubation , bioassay , metyrapone , endogeny , in vitro , adrenocorticotropic hormone , chemistry , dexamethasone , blood plasma , biology , hormone , biochemistry , genetics
SUMMARY The disappearance in vitro of ACTH from whole human blood and plasma held at 22°C has been monitored using a dispersed adrenal cell bioassay and an unextracted radioimmunoassay. In three normal subjects after a metyrapone test and two patients with Addison's disease, endogenous bioactive ACTH levels were unchanged for at least 1 h in blood and 2 h in plasma. Moreover < 50% of the bioactive plasma ACTH was still present in the plasma samples from the patients with Addison's disease after 24 h incubation at ambient temperatures. Human pituitary ACTH (1–39), spiked into plasma from dexamethasone suppressed subjects to give a concentration of 250 ng/1, was stable by bioassay for at least 2 h. No loss of biological activity was observed on subjecting plasma from a patient with Addison's disease or spiked plasma to two cycles of thawing at 37°C and freezing at — 70°C or thawing at 20°C and freezing at — 20°C. Some loss of bioactivity (20%) occurred on subjecting the patient's, but not ACTH‐spiked plasma to four cycles of thawing at 20°C/freezing at — 20°C. We conclude that bioactive ACTH (endogenous or exogenous) may be more stable in vitro in human blood and plasma than has been previously thought. If our studies can be confirmed in a larger series then it may be that conditions for handling blood specimens for ACTH assays could be reappraised.