常规维持量补充肌酸对大鼠内源性肌酸合成的影响

目的:探讨常规维持量补充肌酸(0.15g/kg/d)对大鼠内源性肌酸生物合成系统的影响。方法:将100只SD大鼠按体重随机分为10组:5组为训练组,分别以0、0.03750、.075、0.15和0.3g/kg/d剂量补充肌酸4周。其余5组为相应对照组(补充肌酸、不运动)。训练组大鼠进行4周游泳训练。4周后测定各组大鼠肾脏精氨酸-甘氨酸转脒基酶(AGAT)的活性,肾脏、肝脏和血清胍乙酸(GA)含量,肾脏、血清和骨骼肌肌酸含量,骨骼肌和血清肌酸激酶(CK)活性以及血清肌酐含量。结果:0.075g/kg/d及其以上剂量补充肌酸4周即可抑制训练组和对照组大鼠肾脏AGAT活性(P<0.05),显著降低其肾脏和肝脏胍乙酸含量(P<0.01);训练组大鼠肾脏AGAT活性,肾脏和肝脏胍乙酸含量显著高于对照组(P<0.05,P<0.01)。结论:常规维持量补充肌酸(0.15g/kg/d)可抑制运动训练和非训练大鼠内源性肌酸生物合成系统。

Influence of Routine Maintaining Dose of Creatine Supplementation on Rats' Endogenous Creatine Biosynthesis

Objective To explore the influence of supplementation of creatine with routine maintaining dose(0.15g/kg/d) on the endogenous creatine biosynthesis in rats.Methods The experimental rats swum 4 hours per day and were supplied respectively with different doses of creatine(0,0.0375,0.075,0.15 and 0.3g/kg/d) for 4 weeks(trained group);and the control rats sedentary and treated with creatine exactly the same as the experimental rats(untrained group).Changes in the activities of arginine:glycine amidinotransferase(AGAT),rate-limiting enzyme,and contents of main metabolites of creatine endogenous biosynthesis in both trained and untrained groups of rats were observed.Results The creatine supplementation at the dose of or higher than 0.075g/kg/d for 4 weeks could markedly inhibit AGAT activities in kidneys(P<0.05) and significantly lower guanidinoacetic acid contents in kidney and liver(P<0.01) in both of the trained and untrained groups.Sighificant increases in the AGAT activitiy in kidney(P<0.05) and in guanidinoacetic acid contents in kidney and liver(P<0.01) were observed in the trained group,as compared with that untrained group.Conclusion The routine maintaining dose(0.15g/kg/d) of creatine supplementation inhibited the endogenous biosynthesis of creatine both in trained and untrained groups.