Browsing by Author "Knopp, Robert H."

The effects of late pregnancy on adipose 1etabolism have been examined in fed and fasted mbar fat was excised from 19-day pregnant and ched virgin rats which had been given un- :d access to food ("fed") or fasted for 48 h,:- acrifice. e fed state, adipose tissue from pregnant rats d an increased content of free fatty acids (FFA). incided with augmented cleavage of preformed es during incubation in vitro as evidenced by net production of FFA and glycerol, and altered on of labeled glucose. The enhanced Jipolysis ependent of the availability of glucose and was ,mpanied by impaired responsiveness to the autior to the lipogenic actions of added insulin. In ence of glucose and albumin, csterificatioi:t as well ·sis was greater in adipose tissue from pregnant 1gravid animals. All the differences were exagby prier fasting. properties of adipose tissue during late gestae been ascribed to a primary activation of lipolyer than impaired esterification or resistance to It has been suggested that the hormones of cy may be responsible. Although increased infood and heightened availability of insulin may offset the net lipolytic effects in the fed state, a heightened turnover of adipose stores is always present. Thus, the pregnant animal appears better poised to mobilize preformed fat whenever exogenous nutriens are withheld.

The purpose of this review is to consider the alterations occurring in lipoprotein metabolism in human pregnancy and in selected animal models and to attempt to understand the reasons for these changes and the possible significance for maternal physiology and fetal growth and development. The effects of diabetes mellitus on the system will be briefly considered.

The general features of carbohydrate metabolism during pregnancy may be summarized as follows (J): in the pregnant female with adequate pancreatic reserve, tolerance to intravenous glucose is normal whereas the hypoglycemic response to exogenous insulin is subnormal. The hypoglycemic effectiveness of endogenous insulin also may be diminished as judged by the subnormal lowering of blood sugar after intravenous tolbutamide. The dichotomy would suggesc that an enhanced elaboration of endogenous insulin is required to maintain normal glucose tolerance during pregnancy. The histologi,: al finding of islet cell hyperplasia during normal gestation, and the clinical experience in subjects with marginal or absent pancreatic islet cell reserve are in accord with this premise.