Warren N. Dannenburg

Control of Plasma Non-Esterified Fatty Acids in Pregnancy and the Puerperium.

Summary The amount and timing of glucose administered to fasting post partum women receiving intravenous insulin determines the amount and direction of change in plasma NEFA. Twenty-five grams of glucose inhibits the characteristic response of NEFA to insulin while half this dosage either enhances the insulin effect or causes secondary decrements in non-esterified fatty acid. These results suggest that the regulation of plasma NEFA is a complex function that may involve fatty acid synthesis, utilization and recycling as well as controlled release from fat depots.

THE EFFECT OF INSULIN AND GLUCOSE ON PLASMA LIPIDS DURING PREGNANCY AND THE PUERPERIUM.

Summary 1. Evidence was presented that confirmed the hyperlipidemia of pregnancy and showed that with the exception of esterified cholesterol, significant decrements occurred in the fasting levels of plasma lipids by the fourth postpartum day. 2. The mean changes in plasma levels of triglycerides, free cholesterol, and lipid phosphorus in nonpregnant, pregnant, and puerperal subjects differed significantly in their responses to insulin and/or glucose. 3. Mean changes in cholesterol ester were not attributed to the differential response of the 3 groups to insulin and glucose, but appeared to be related to the free cholesterol levels. 4. Analysis of variance revealed that with the exception of lipid phosphorus levels, the mean changes in the plasma lipids were attributable to factors other than the group × treatment interaction. 5. Glucose metabolism during pregnancy was altered in favor of cholesterolgenesis, and it was indicated this difference was due to impaired carbohydrate metabolism through the dissociation of the effect of insulin on extrahepatic tissue. 6. The relative amounts of insulin and glucose were reflected in the plasma levels of free cholesterol in pregnant and puerperal subjects.

Plasma lipids in the early puerperium

Abstract Plasma lipids for nonpregnant and puerperal patients were resolved on silicic acid columns into triglyceride, phospholipid, and cholesterol ester fractions, and the esterified fatty acids in these fractions determined. Results showed that, with the exception of esterified cholesterol, puerperal values for the carboxyl esters increased during the 24 hours following delivery. In addition, a decrease was observed in these lipid components from the first through the fifth postpartum day which was primarily due to the triglycerides, though phospholipid and esterified cholesterol showed a slight drop. Impaired carbohydrate metabolism and its possible relation to insulin resistance was suggested as a factor explaining the hyperlipidemia of pregnancy and its decrease in the early puerperium.

Plasma nonesterified fatty acids in pregnancy: III. Further observations on regulation of plasma NEFA concentration by insulin and glucose

Abstract 1. The effect of various combinations of glucose and insulin on plasma NEFA concentrations were tested in normal pregnant, early puerperal, and nonpregnant subjects. 2. The responses observed in plasma NEFA were dependent upon the amount of glucose administered as well as the time of glucose loading in relation to that of insulin administration. Small amounts of glucose tended to enhance NEFA falls in plasma, while larger glucose dosages produced smaller changes or stabilized the fatty acid level. 3. The relative amounts of carbohydrate and insulin rather than the degree of hyperglycemia and hypophosphatemia appeared to determine the amount and direction of change in NEFA concentration. The experimental results are discussed in terms of the known factors determining NEFA oxidation, esterification, and release by adipose tissue. 4. Within a few days after the onset of labor the concentration of plasma NEFA is increased and its regulation is extremely labile as indicated by its sensitivity to experimental modification. This lability is not observed in the early puerperium. 5. Intravenous glucose tolerance data are not influenced by pregnancy in metabolically normal patients despite evidence of decreased reactivity to exogenous insulin.

LIPID COMPOSITION AND SYNTHESIS IN RAT LIVER DURING PREGNANCY AND THE PUERPERIUM.

Summary The composition and incorporation of acetate-1-C14 into liver lipids of non-pregnant, pregnant, and puerperal rats were determined. Results show that total cholesterol and phospholipid phosphorus in rat liver during pregnancy and the puerperium do not differ from those found in non-pregnant animals. However, the triglycerides from livers of puerperal animals were significantly higher than those found in either non-pregnant or pregnant rats. Incorporation of acetate-1-C14 into fatty acids and unsaponifiable substances by liver slices from pregnant rats was significantly greater than that observed for non-pregnant and puerperal rats. No differences were observed in the μmoles of acetate incorporated into the fatty acids of triglycerides and phospholipids. Possible factors related to the puerperal increase of triglycerides in the liver are discussed.

Carotene and Vitamin A in Pregnancy and the Early Puerperium.

Summary 1. Levels of carotene and vit. A in pregnant patients were shown to be significantly different from those found in nonpregnant and puerperal patients. 2. Differences in the means of carotene and vit. A between puerperal and non-pregnant patients were variable and it appeared that changes in carotene and vit. A following delivery are rapid and not significantly different from those found in the non-pregnant group. No differences were found in carotene and vit. A between postpartum days. 3. Diet was apparently not a factor influencing carotene and vit. A levels in this study. 4. Evidence was given supporting the inverse relationship between carotene and vit. A and it was suggested that the ratio (C/A) of these components may be a better parameter for detecting changes occurring in their metabolism. 5. The possible association of vit. A and carotene changes with changes in lipids during pregnancy was considered.

Fatty acid composition of plasma lipid fractions in the early puerperium

Abstract 1. 1. Fatty acids in the cholesterol ester and triglyceride plasma fractions of nonpregnant and puerperal subjects on the day of delivery and the 5 succeeding days were converted to their methyl esters. The latter were separated by gas liquid chromatography and the proportions of plamitic, palmitoleic, stearic, oleic, and linoleic acids (16:0, 16:1, 18:0, 18:1, and 18:2, respectively) in the fatty acids of the two fractions were determined. 2. 2. On the day of delivery the proportions of 16:0 and 18:1 in the cholesterol ester fraction were significantly higher, and that of 18:2 was significantly lower than in the nonpregnant subjects. At the same time in the triglyceride fraction the proportion of 16:0 was significantly greater, while those of 18:0 and 18:1 were lower than in nonpregnant patients. These differences resemble those reported between nonpregnant subjects and those with diabetes or arteriosclerosis who showed hyperlipidemia. 3. 3. During the early puerperium the patterns of fatty acids in the two fractions changed. Changes in proportion of 18:1 in the cholesterol fraction and of 16:0 in the triglyceride fraction were statistically significant. 4. 4. The previously reported increase from the day of delivery to the first postpartum day in plasma concentration of fatty acids in the triglyceride fraction was found to be largely due to 16:0 and 18:1. Each of the five fatty acids contributed to the decrease during the same time in level of fatty acids in the cholesterol ester fraction.

Vitamin A ester and alcohol of rat liver during pregnancy.

Summary During pregnancy plasma Vit. A decreased and liver Vit. A alcohol increased but both returned to prepregnant values by the second postpartum day. The data indicate that an inverse relationship exists in pregnancy between plasma Vit. A and liver Vit. A alcohol that is unrelated to esterified Vit. A, body weight, and liver hypertrophy. It was suggested that changes in plasma Vit. A levels were related to transport and secondary to the hyperlipidemia of pregnancy. A possible mechanism involved is discussed.