The Free Amino Acids of Serum During Development of Macaca mulatto II. During Pregnancy and Fetal Life

Abstract

The levels of free amino acids of serum have been investigated during pregnancy and fetal life in the rhesus monkey (Macaca mulatta). Samples of venous blood were drawn simultaneously from the mother and the umbilical cord of the fetus at cesarian section delivery performed at exactly 50, 75, 100, 125, and 150 days conceptual age and at full-term vaginal delivery (168+4 days). Although a wide range of values was found for each amino acid at each age studied (tables I and II), certain trends were evident. All levels of maternal amino acids except those for taurine, lysine, 3-GH 3 -histidine and arginine were lower at full-term pregnancy than they were in nonpregnant adult animals. This pattern was apparent by 75 days of gestation and was maintained without further change during the remainder of pregnancy.The sum of the individual values of all free amino acids in fetal blood was highest at 75 days of gestation; this resulted primarily from elevated levels of glutamine and glutamic acid, histidine, methionine, and valine. Levels of 3-GH 3 -histidine and glycine showed the opposite trend and were higher during late pregnancy than at 75 days of fetal age. The levels of the other amino acids did not undergo significant changes throughout gestation.At each age studied, the level of each amino acid in fetal blood was higher than that of the corresponding level in maternal blood. The umbilical cord: maternal ratios for alanine, glutamine plus glutamic acid, leucine, 3-GH 3 -histidine and valine were significantly elevated at the earliest gestational age. The mean cord: maternal value for all amino acids studied showed a progressive decrease with increasing fetal maturity.

Amino acid metabolism during starvation in human pregnancy

“…The current data indicate that in physically healthy, unanesthetized women, a significant reduction in the postabsorptive levels of most amino acids occurs by wk 16-20 of gestation. In accordance with these findings in humans are recent observations in subhuman primates, in whom gestational hypoaminoacidemia is manifest by midpregnancy with no further reduction in amino acid levels occurring as pregnancy progresses to term (26). The unique increase in postabsorptive levels of histidine in the pregnant group is in keeping with previous demonstrations of relative or absolute hyperhistidinemia during late pregnancy in women (25), and in monkeys studied at various stages of gestation (26).…”

Carbohydrate metabolism in pregnancy

“…Several of these steps may be attenuated during late pregnancy. Plasma amino acids are diminished in the gravid rat (5), as in the pregnant primate (50), and hepatic alanine a-ketoglutarate transaminase activity is reduced (5 21 of gestation) with postpartum (i.e. PP; from day 10 to 11 and 11 to 12 after delivery).…”

Medical Therapy For Pulmonary Arterial Hypertension

“…In addition, it is clear that the amino acid, L-arginine, is the sole substrate for NOS and thus is essential for NO production. It is estimated that the average diet is borderline in arginine content, 111,112 and circulating levels can be reduced by administration of arginine-deficient protein, 111,112 by pregnancy, [113][114][115][116][117] aging, 118 or stress. 118 Still, in vivo arginine levels have been thought to be more than sufficient for NO synthesis because at usual plasma levels of 50 to 100 mol/L, active transport produces intracellular levels of 1,000 mol/L, which vastly exceed the Km for NOS of 1 to 3 mol/L.…”