Adrenocorticotrophin and corticosteroid changes during dexamethasone infusion to intact and synacthen infusion to hypophysectomized foetuses.
Synacthen has been infused at 10 microgram/h into 4 hypophysectomized foetal sheep. This caused a rise in adrenocorticotrophin to a mean value of 512 pg/ml which remained fairly constant and did not show the large fluctuations seen on infusion into intact foetuses. The Synacthen half-life in the circulation had a mean value of 0.27 min. Hypophysectomy did not necessarily delay the foetal corticosteroid response to Synacthen infusion. The corticosteroid concentration achieved had a mean value of about 50 ng/ml which is substantially below that for intact foetuses and in one case it was maintained at only 20 ng/ml. Despite this delivery occurred within 5 days. Dexamethasone infusion reduced the plasma adrenocorticotrophin concentration by about 70% and the plasma cortisol concentration by about 60%.
D000305:Adrenal Cortex Hormones / Q000097:blood*; D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000097:blood*; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D003366:Cosyntropin / Q000097:blood / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005333:Fetus / Q000187:drug effects*; D006207:Half-Life; D006801:Humans; D007016:Hypophysectomy; D007752:Obstetric Labor, Premature; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011247:Pregnancy; D012756:Sheep
D000305:Adrenal Cortex Hormones; D002245:Carbon Dioxide; D003366:Cosyntropin; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D010100:Oxygen