title: The effect of atropine on heart rate and oxygen consumption of the hypoxic fetus.
abstract: To determine if vagal blockade during hypoxic bradycardia improves fetal oxygenation, 10 studies were carried out on five chronically instrumented sheep after 0.8 week of gestation. At a mean maternal arterial oxygen tension of 33 +/- 4 mm Hg, the fetal heart rate decreased 20% to 137 +/- 19 bpm, and fetal oxygen consumption decreased 42% to 4.6 +/- 1.5 ml/min/kg of fetus. After 200 micrograms atropine was infused into a fetal vein, fetal heart rate increased immediately to 249 +/- 26 bpm. Fetal oxygen consumption was unchanged. Fetal heart rate increased by 18 bpm after atropine in the normoxic fetus. These studies show that there is a substantial bradycardia due to an increase in vagal activity during hypoxia in the fetus and that blockade of this activity causes a marked tachycardia but no increase in fetal oxygen uptake.
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D005260:Female; D005318:Fetal Heart / Q000187:drug effects; D005311:Fetal Hypoxia / Q000503:physiopathology*; D005333:Fetus / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects*; D011247:Pregnancy; D012756:Sheep; D014469:Umbilical Arteries
chemical_list: D001285:Atropine