高温对小鼠血清游离氨基酸的影响

本实验观察了高温环境下小鼠血清游离氨基酸的变化。结果显示：１。小鼠热应激１ｈ后，肛温平均增高２．５℃，血清绝大多数游离氨基酸（ＦＡＡ）浓度急剧上升，特别是必需氨基酸（ＥＨＡＡ）的浓度、比值增高幅度最大，总游离氨基酸（ＴＡＡ）、支链氨基酸（ＢＣＡＡ）、芳香氨基酸（ＡＡＡ）都高于常温对照组，反映在热应激下机体蛋白质处于高分解代谢；２．热习服后大多数ＦＡＡ在对照组水平，表明热习服后组织蛋白质的分解与合成趋向平衡。血清中ＥＡＡ、ＡＡＡ及精、酪氨酸浓度及比值明显低于对照组，提示长时间热暴露机体对这些氨基酸代谢量增加；３．谷氨酰胺和酪氨酸可能是促进热习服的主要氨基酸，而精氨酸对提高耐热能力，消除疲劳可能具有重要作用。

INFLUENCE OF HIGH TEMPERATURE ON FREE AMINO ACIDS IN MICE SERUM

he changes of free amino acids in mice serum under high temperature were observed.The results showed:1.Serum levels of all amino acids were elevated except arginine in heat stress(HS).The changes were the highest in branched- chain amino acids(BCAA)and then lysine,tyrosine,tryptophan,glycine + threonine, serine and methionine(P<0.001)。2. Most of free amino acids in mice serum after heat acclimatization(HA)were lower than those of HS group,among which changes of BCAA and aromatic amino acids (AAA),tvrosine was the most significant(P<0.05)。3.The values of four indices,total serum free anlino acids (TAA),10 essential amino acids(EAA),BCAA and AAA were significantly higher in HS group than the control and HA groups(P<0.05).As the mice had been adapted to high temperature environment,serum levels of TAA and BCAA were slightly higher than control group,EAA was slightly lower than control group,and AAA was significantly lower as compared with the control(P<0.05)The metabolism in HS group was characterized by enhanced proteo- lysis of tissue protien,Through a 9-day exposure to heat,adaptive changes took place in mouse body. Serum levels of free amino acids were restored to normal and total amount of EAA was lower than the control,showing that proteolytic and synthetic metabolism of tissue protein tended to be ba- lanced.Serum EAA,arginine and tyrosine were decreased after HA,illust- rating an elevated requirement of these amino acids for mice in hot environ- ment。Glutamine and tyrosine might be the major amino acids for promotion of HA,Arginine might exert important actions on taugmenting heat toleran- ce and eradicating fatigue。