Low Doses of Dexamethasone Suppress Pituitary-Adrenal Function but Augment the Glycemic Response to Acute Hypoxemia in Fetal Sheep during Late Gestation
| Autor: | Alison J. Forhead, Abigail L. Fowden, Andrew J. W. Fletcher, Mark R Goodfellow, HH McGarrigle, David S. Gardner, Dino A. Giussani |
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| Rok vydání: | 2000 |
| Předmět: |
Blood Glucose
medicine.medical_specialty Hydrocortisone medicine.drug_class medicine.medical_treatment Pituitary-Adrenal System Aorta Thoracic Gestational Age Dexamethasone Hypoxemia Hemoglobins Catheters Indwelling Fetus Adrenocorticotropic Hormone Pregnancy Internal medicine medicine Animals Hypoxia Infusions Intravenous Maternal-Fetal Exchange Saline Acid-Base Equilibrium Sheep Dose-Response Relationship Drug business.industry Gestational age Carotid Arteries Endocrinology embryonic structures Pediatrics Perinatology and Child Health Corticosteroid Gestation Female Blood Gas Analysis medicine.symptom business Glucocorticoid medicine.drug |
| Zdroj: | Pediatric Research. 47:684-691 |
| ISSN: | 1530-0447 0031-3998 |
| DOI: | 10.1203/00006450-200005000-00021 |
| Popis: | Despite the widespread use of antenatal glucocorticoid therapy in obstetric practice, little is known about the effects of synthetic glucocorticoids on the fetal capacity to respond to episodes of acute hypoxemia, such as may occur during labor and delivery. This study investigated the effects of prolonged fetal exposure to low concentrations of dexamethasone on the fetal ACTH, cortisol, and glycemic responses to an episode of acute hypoxemia during the period of dexamethasone treatment in sheep. At 118 d of gestation (term is approximately 145 d), 11 fetal sheep had catheters implanted under halothane anesthesia. From 124 d, five fetuses were infused i.v. continuously with dexamethasone (1.80 +/- 0.15 microg x kg(-1) x h(-1) in 0.9% saline at 0.5 mL/h) for 48 h, and the other six fetuses received saline solution i.v. at the same rate. At 45 h of infusion, acute hypoxemia was induced in all fetuses for 1 h by reducing the maternal inspired fraction of oxygen. During glucocorticoid treatment, fetal plasma dexamethasone concentrations increased to 3.9 +/- 0.2 nM by 24 h and remained elevated for the rest of the infusion period. During hypoxemia, a similar fall in fetal arterial PO2 occurred in both saline-infused and dexamethasone-treated fetuses. In control fetuses, significant increases in plasma ACTH and cortisol concentrations and in blood glucose concentrations occurred during hypoxemia. Dexamethasone treatment prevented the increases in fetal plasma ACTH and cortisol, and augmented the blood glucose response, induced by hypoxemia. These data indicate that prolonged fetal exposure to low concentrations of dexamethasone suppresses pituitary-adrenal function, but augments the glycemic response, to acute hypoxemia in fetal sheep during late gestation. |
| Databáze: | OpenAIRE |
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