The effect of hypobaric hypoxaemia on the concentration of metabolic substrates in the ovine fetus and pregnant ewe with implanted
vascular catheters, was investigated. At 120 to 141 days of gestation sheep were subjected to hypobaria (mean fetal carotid PO2 12.7 +/- 0.7 torr; n = 9) or normobaria (mean fetal carotid PO2 22.7 +/- 0.7 torr; n = 11; P less than 0.001). At 141 days gestation mean
fetal weight was 3.46 +/- 0.72 kg in the hypobaric group compared to 4.15 +/- 0.51 in the normobaric group (P less than 0.05). Concentrations of
glucose in maternal and fetal plasma and
fructose in fetal plasma were similar in hypobaric and normobaric fetuses. The concentration of
lactate in fetal plasma rose from 1.68 +/- 1.34 to 8.79 +/- 5.8 mmol/l (P less than 0.001) within 24 h of onset of
hypoxia, but fell to 3.36 +/- 1.13 mmol/l by day 3 of treatment, though still significantly above the concentration of
lactate in the control fetuses (1.47 +/- 0.47; P less than 0.001). There was no significant effect of
hypoxia on the concentration of
lactate or
alanine in maternal plasma.
Alanine concentration in the plasma of fetuses subjected to
hypoxia significantly increased within 24 h of exposure (0.28 +/- 0.10 vs 0.58 +/- 0.39 mmol/l; P less than 0.01) and remained elevated for the duration of the study. There was no significant effect of gestational age on the concentration of metabolic substrates in either the control or experimental groups.
Hypoxia is associated with a sustained rise in the concentration of plasma
lactate and
alanine in the fetus.(ABSTRACT TRUNCATED AT 250 WORDS)