Manso Filho Hélio C, Costa Helena E, Wu Guoyao, McKeever Kenneth H, Watford Malcolm
Equine Science Center, Department of Animal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
Vet Res Commun. 2009 Feb;33(2):175-82. doi: 10.1007/s11259-008-9167-2. Epub 2008 Aug 23.
In most mammalian species the developing fetus utilizes large amounts of glutamine derived both from the maternal circulation and synthesized de novo in the placenta. The present study was designed to determine the role of the placenta in glutamine synthesis in the horse. The placentae from eight Standardbred mares were sampled immediately after parturition together with additional tissues obtained at necropsy from three Standbred mares during diestrous. Glutamine synthetase protein was detectable in the non-pregnant horn of the placenta in amounts similar to those seen in gluteus muscle, but the amount in the pregnant horn was two times greater than in the non-pregnant horn. Glutamine was the second most abundant amino acid in amniotic fluid at a concentration of 310 +/- 26 micromole/L with that of glycine being 535 +/- 48 micromole/L. The most abundant amino acids in placental tissue were glycine (3,732 +/- 194 micromole/Kg), glutamate (3,500 +/- 343 micromole/Kg) and glutamine (2,836 +/- 208 micromole/Kg). The results illustrate the importance of glutamine to the equine fetus and establish that the placenta, particularly the pregnant horn, has considerable capacity for glutamine synthesis.
在大多数哺乳动物物种中，发育中的胎儿会利用大量来自母体循环以及在胎盘中重新合成的谷氨酰胺。本研究旨在确定胎盘在马体内谷氨酰胺合成中的作用。八匹标准赛马母马的胎盘在分娩后立即取样，另外还从三头处于间情期的标准赛马母马尸检时获取了其他组织。在胎盘的非孕角中可检测到谷氨酰胺合成酶蛋白，其含量与臀肌中的相似，但孕角中的含量比非孕角中的高两倍。羊水中第二丰富的氨基酸是谷氨酰胺，浓度为310±26微摩尔/升，甘氨酸的浓度为535±48微摩尔/升。胎盘组织中最丰富的氨基酸是甘氨酸（3732±194微摩尔/千克）、谷氨酸（3500±343微摩尔/千克）和谷氨酰胺（2836±208微摩尔/千克）。这些结果说明了谷氨酰胺对马胎儿的重要性，并证实胎盘，尤其是孕角，具有相当大的谷氨酰胺合成能力。
