PMID: 591480Nov 1, 1977

Placental diffusing capacity for carbon monoxide and oxygen in unanesthetized sheep

Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology
L D Longo, K S Ching

Abstract

We measured placental diffusing capacity for carbon monoxide (DpCO) in 10 unanesthetized sheep with catheters chronically implanted in maternal and fetal vessels. Serially measured DpCO during the last third of gestation averaged 0.55 +/- 0.02 (SEM) ml.(min.Torr.kg fetal wt)-1, essentially the same value as that previously reported in anesthetized, acutely operated animals. While placental CO diffusing capacity increased as a function of gestational age when expressed as ml.(min.Torr)(-1), it remained constant when calculated per kg fetal wt. In eight experiments, DpCO showed no change following the administration of several drugs which combine with cytochrome P450. We interpret this as evidence against the carrier hypothesis for placental CO exchange. We calculated the placental diffusing capacity for oxygen to be 0.68 ml.(min.Torr.kg)-1 and the mean maternal-to-fetal capillary Po2 difference to be 10 Torr. Caculations predict that maternal and fetal oxygen partial pressures equilibrate in end-capillary blood during the course of a single transit in placental exchange vessels; thus placental oxygen exchange is not limited by diffusion.

Citations

Apr 20, 2019·Science Advances·Alexander ErlichIgor L Chernyavsky
Oct 1, 1984·Teratology·J Singh, L H Scott
Jan 6, 2010·Reproduction, Fertility, and Development·Natalee W Bessette, Dan W Rurak
Jan 1, 1995·Journal of Basic and Clinical Physiology and Pharmacology·H Sohmer, S Freeman
Jan 1, 2013·Annual Review of Animal Biosciences·Anthony M Carter, Allen C Enders
Dec 16, 2011·BMC Pregnancy and Childbirth·Carolina C VendittiGraeme N Smith
May 1, 1982·Journal of Toxicology. Clinical Toxicology·C R Cramer

Related Concepts

Carbon Monoxide
Cytochrome P-450 Oxygenase
Diffusion
Gestational Age
Maternal-Fetal Exchange
Mathematics
Oxygen Consumption
Placenta
Dall Sheep

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