Uterine metabolism of the conscious gilt during late pregnancy.

The present study provides some metabolic features of the gravid uterus in the nonanesthetized gilt during the last fourth portion of pregnancy. Substrate and oxygen arteriovenous differences across the uterus were determined in eight gilts with chronically implanted arterial and uterine venous catheters. Glucose represents the main substrate taken up by the conceptus and glucose extraction amounts to 8.3 +/- 0.5%. By contrast, there is a constant release of lactate from the pregnant uterus. The coefficient of extraction of oxygen is 20.2 +/- 1.9%. Glucose plus lactate/oxygen quotient is high (1.3 +/- 0.2), suggesting that glucose alone is sufficient to account for the oxidative metabolism of the pig uterus. Nonesterified fatty acid and ketone body are not significantly extracted by the pig uterus whereas a significant amino acid extraction occurs in late pregnancy. Uterine uptake of amino acids depends on maternal arterial concentrations and a great part (78%) of this uterine uptake is represented by neutral amino acids and especially glutamine.