PMID- 9530119 OWN - NLM STAT- MEDLINE DCOM- 19980424 LR - 20190423 IS - 0002-9513 (Print) IS - 0002-9513 (Linking) VI - 274 IP - 3 DP - 1998 Mar TI - Cortisol infusion depresses the ratio of bioactive to immunoreactive ACTH in adrenalectomized sheep fetuses. PG - E391-6 LID - 10.1152/ajpendo.1998.274.3.E391 [doi] AB - We examined the effects of exogenous cortisol on plasma immunoreactive adrenocorticotropic hormone (iACTH), bioactive ACTH (bACTH), and ACTH-(1-39) in nine adrenalectomized fetuses at 126-130 and 136-140 days of gestation. Fetuses received 4 h of cortisol (2 micrograms.kg-1.min-1) or saline infusions on consecutive days. Blood was obtained before and at intervals during infusions. Arterial blood gases and hematocrits were normal and did not change with age. Plasma cortisol did not change during saline infusions but increased significantly (range 30-70 ng/ml) during cortisol infusions. Basal plasma iACTH, bACTH, ACTH-(1-39), and bACTH-to-iACTH and ACTH-(1-39)-to-iACTH ratios were significantly higher in the older fetuses. Cortisol infusions decreased plasma iACTH, bACTH, and ACTH-(1-39) in both groups, and the suppression as a percent of the baseline was similar. The bACTH-to-iACTH ratio declined to the same level at 126-130 (0.201 +/- 0.040 to 0.051 +/- 0.002) and 136-140 (0.389 +/- 0.088 to 0.046 +/- 0.002) days of gestation. These data suggest that physiological concentrations of cortisol selectively inhibit bACTH secretion, and the ACTH response to cortisol inhibition is not different between 126 and 140 days of gestation in adrenalectomized sheep fetuses. FAU - Zehnder, T J AU - Zehnder TJ AD - Department of Physiology and Pharmacology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157-1066, USA. FAU - Valego, N K AU - Valego NK FAU - Schwartz, J AU - Schwartz J FAU - Green, J AU - Green J FAU - Rose, J C AU - Rose JC LA - eng GR - R01 HD017644/HD/NICHD NIH HHS/United States GR - HD-11210/HD/NICHD NIH HHS/United States PT - Journal Article PT - Research Support, U.S. Gov't, P.H.S. PL - United States TA - Am J Physiol JT - The American journal of physiology JID - 0370511 RN - 9002-60-2 (Adrenocorticotropic Hormone) RN - WI4X0X7BPJ (Hydrocortisone) SB - IM MH - Adrenal Glands/embryology MH - Adrenalectomy MH - Adrenocorticotropic Hormone/*blood MH - Animals MH - Blood Gas Analysis MH - Fetus/*metabolism MH - Gestational Age MH - Hematocrit MH - Hydrocortisone/administration & dosage/blood/*pharmacology MH - Hydrogen-Ion Concentration MH - Immunoradiometric Assay MH - Infusions, Intravenous MH - Longitudinal Studies MH - Radioimmunoassay MH - Sheep EDAT- 1998/04/08 00:00 MHDA- 1998/04/08 00:01 CRDT- 1998/04/08 00:00 PHST- 1998/04/08 00:00 [pubmed] PHST- 1998/04/08 00:01 [medline] PHST- 1998/04/08 00:00 [entrez] AID - 10.1152/ajpendo.1998.274.3.E391 [doi] PST - ppublish SO - Am J Physiol. 1998 Mar;274(3):E391-6. doi: 10.1152/ajpendo.1998.274.3.E391.