Insignificant response of the fetal placental circulation to arterial hypotension in sheep

J. J. Faber, D. F. Anderson, S. Louey, K. L. Thornburg, G. D. Giraud

    Research output: Contribution to journalArticlepeer-review

    3 Scopus citations


    Infusion of the angiotensin-converting enzyme inhibitor enalaprilat into fetal sheep caused a profound arterial hypotension within days. Five fetal lambs were infused with enalaprilat for 8 days starting at day 128 of gestation. Total accumulated dose was 0.30 ± 0.11 mg/kg. Arterial pressure decreased from 43.6 to 25.6 mmHg; venous pressure did not change. Biventricular output was not statistically significantly changed; placental blood flow decreased almost in proportion to the decrease in pressure but the increase in somatic flow was not statistically significant. There were no significant changes in pressure 30 min after the initial 50-±g loading dose of enalaprilat. However, the arterial pressure responses to test doses of ANG I were largely abolished. After 1 day, however, there was a significant decrease in somatic vascular resistance, which became stronger with time, but almost no decrease in the placental resistance. We conclude that the fetal somatic circulation exhibits a slow but strong decrease in resistance but that the response to hypotension is weak or absent in the fetal placenta, possibly because it is already fully relaxed.

    Original languageEnglish (US)
    Pages (from-to)1042-1047
    Number of pages6
    JournalJournal of Applied Physiology
    Issue number4
    StatePublished - Oct 2011


    • Blood gases
    • Enalaprilat
    • Growth
    • Plasma renin activity
    • Somatic blood flow
    • Vascular resistance

    ASJC Scopus subject areas

    • Physiology
    • Physiology (medical)


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