title: Catecholamine physiology in ovine fetus. II. Metabolic clearance rate of epinephrine.
abstract: This study measured the metabolic clearance rate (MCR) of epinephrine (E) in 13 chronically catheterized fetal lambs between 120 and 145 days gestation. The E-MCR was determined by a constant infusion method at an E infusion rate of 0.1 microgram/kg estimated fetal wt. Fetal and maternal arterial blood samples were taken for measurements of catecholamine levels, pH, blood gases, and glucose. There was a significant positive correlation between gestational age and E-MCR (r = 0.87, P less than 0.001). The E production rate in fetuses less than 132 days (n = 6) (1,234 +/- 301 pg/min) was not significantly different from fetuses greater than or equal to 132 days (n = 7) (1,195 +/- 242). Catecholamine infusion resulted in a decrease in pH from a control value of 7.37 +/- 0.01 to 7.31 +/- 0.01 by 15 min of infusion, but there were no significant changes in fetal heart rate or blood pressure. The mean fetal plasma glucose concentration increased 45% above base line at 15 and 20 min and 65% above base line by 30 min of catecholamine infusion. After 60 min of infusion plasma norepinephrine (NE) increased from 380 +/- 60 to 520 +/- 75 pg/ml and plasma dopamine from 100 +/- 20 to 240 +/- 50 pg/ml (both P less than 0.05). These results indicate that E-MCR increases with maturation in the absence of a change in basal E production.
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004298:Dopamine / Q000097:blood; D004837:Epinephrine / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000502:physiology; D005865:Gestational Age; D006339:Heart Rate; D008657:Metabolic Clearance Rate; D009638:Norepinephrine / Q000097:blood; D011247:Pregnancy; D012756:Sheep / Q000196:embryology*
chemical_list: D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine