PRETERM NEWBORN LAMB RENAL AND CARDIOVASCULAR-RESPONSES AFTER FETAL OR MATERNAL ANTENATAL BETAMETHASONE

The optimal dose, route of administration, and treatment-to-delivery i nterval necessary to induce beneficial extrapulmonary effects of gluco corticoids are not known. Pregnant ewes (127 days gestation) were rand omized to receive maternal or fetal intramuscular injections of betame thasone (0.2 or 0.5 mg/kg body wt) or saline 24 h before cesarean deli very of their lambs. Three hours after delivery, low-dose maternal vs. control lamb mean arterial pressure [64 +/- 4 vs. 47 +/- 2 (SE) mmHg] , glomerular filtration rate (1.7 +/- 0.2 vs. 0.7 +/- 0.1 ml.min(-1).k g(-1)), and total renal sodium reabsorption (219 +/- 31 vs. 85 +/- 12 mu eg.min(-1).kg(-1)) were increased. Comparable increases were observ ed in the high-dose maternal and fetal groups without effects in the l ow-dose fetal group. This study provides the first quantitative data d emonstrating that even short-term (24-h) antenatal betamethasone expos ure alters preterm newborn cardiovascular and renal functions. These r esponses are route and dose dependent and are comparable to glucocorti coid-induced maturational effects after longer-term antenatal exposure .