Carbohydrate Metabolism in the Fetal Pig During Late Gestation

¹ The Physiological Laboratory, University of Cambridge, Cambridge, CB2 3EG

In acute experiments on pregnant sows under sodium pentobarbitone anaesthesia, acid base balance, oxygenation and plasma metabolite concentrations were well maintained in the dam and all fetuses which remained undisturbed in utero, irrespective of the duration of the experiment. Fetal liver glycogen concentrations were also unaffected by the time of removal of the fetus. By contrast, intravascular catheterization and withdrawal of blood led to fetal hyperglycaemia and depletion of hepatic glycogen although blood gas and pH values were not changed by these procedures. In the 1-2h sampling period following catheterization the normal positive umbilical venous-arterial differences in plasma glucose and lactate generally became reversed. These changes were prevented by the administration of hexamethonium (10-15 mg.kg^-1 i.v.) but the drug did not block the fall in hepatic glycogen in catheterized fetuses. Both adrenaline and noradrenaline, which were each infused intravenously at 2·7-3·9 or 0·6-0·9 µg.kg^-1.min^-1. resulted in fetal hyperglycaemia and lacticacidemia together with a fall in arterial blood pH; hepatic glycogen concentrations in these fetuses were also reduced. The apparent sensitivity of the glycogenolytic mechanism to surgical trauma and haemorrhage in the fetal piglet is discussed in relation to findings in other species.

Note:

This work was supported by a grant from the Agricultural Research Council. We should like to thank Mr. P. Hughes and Miss T. Grimes for their help during surgery and sampling, Mr. D. Clarke and Mr. R. Eastwood for their care of the animals and Mrs. J. Knox and Mrs. S. Loewenbein for their assistance with the biochemical analyses. Part of the work was carried out during the tenure by Abigail Fowden of a M.R.C. Studentship.