Blood glucose of mother and fetus late pregnancy of rats with glycogen storage disorder.

The gsd/gsd rat is unable to mobilize liver glycogen due to an absence of phosphorylase b kinase activity. Unlike the normal rat, the maternal gsd/gsd rat cannot maintain its blood glucose concentration in late pregnancy, and values of 3.25 +/- 0.22 mM were found just before birth. The blood glucose of the gsd/gsd fetus falls to 1.76 +/- 0.09 mM at day 19 of gestation and does not rise appreciably again before birth. In contrast, normal fetal rats show a steady rise in blood glucose from hypoglycemic levels at day 19 to a value of 5.70 +/- 0.12 mM on the day of birth. These results indicate that the normal fetal rat contributes towards the regulation of its own glucose in late gestation by utilizing its liver glycogen stores.