Beta-adrenoceptor agonists and hypoxia in sheep fetuses

Acta Physiol Scand. 1989 Oct;137(2):291-9. doi: 10.1111/j.1748-1716.1989.tb08750.x.

Abstract

Sheep fetuses, near term, were studied to test the influence of a tocolytic beta agonist, terbutaline, on fetal responses to hypoxia. After fetal exteriorization the drug was administered intravenously to the mother in three different doses: The max group comprised 11 ewes receiving 67-134 micrograms min-1. Seven ewes were given 30 micrograms min-1 and eight ewes were infused with 10 micrograms min-1. Seventeen fetuses served as controls. Hypoxia was induced by intermittent complete occlusions of the maternal abdominal aorta. Maternal terbutaline levels were high (range 50-748 nmol l-1) in the max group and the 30-micrograms group, whereas those in the 10-micrograms group were in the clinical range (range 11-58 nmol l-1). Fetuses in the max and 30-micrograms groups reacted to moderate hypoxia with excessive responses of heart rate, blood pressure myocardial contractility and ST waveform changes and a 50% mortality rate during severe hypoxia as compared with 12% in the control animals. Ten micrograms min-1 did not decrease the survival but caused an increase in myocardial workload and a negative energy balance during severe hypoxia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Pressure / drug effects
  • Female
  • Fetal Hypoxia / blood
  • Fetal Hypoxia / drug therapy
  • Fetal Hypoxia / physiopathology*
  • Heart Rate / drug effects
  • Hemodynamics / drug effects*
  • Myocardial Contraction / drug effects
  • Pregnancy
  • Prognosis
  • Sheep
  • Terbutaline / administration & dosage*
  • Tocolysis

Substances

  • Terbutaline