Polakof Sergio, Soengas José L
Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, 36310 Vigo, Spain.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Oct;151(2):205-10. doi: 10.1016/j.cbpa.2008.06.025. Epub 2008 Jun 29.
The aim of this study was to obtain in rainbow trout evidence for the role of lactate in liver carbohydrate metabolism. In the first experiment fish were injected intraperitoneally (n=8) with 5 mL x kg(-1) of Cortland saline alone (control) or saline containing L-(+)-lactate (22.5 mg x kg(-1) or 45 mg x kg(-1)) with samples being obtained 6 h after treatment. In the second experiment, to isolate the effects of increased lactate levels alone from the possible in vivo interaction of increased lactate levels with the effect of hormones and metabolites other than glucose, small liver pieces were incubated in vitro for 1 h at 15 degrees C in modified Hanks' medium containing 2, 4 or 8 mM L-(+)-lactate alone (control) or with 50 mM oxamate, 1 mM DIDS, 1 mM dichloroacetate (DCA), 10 mM 2-deoxyglucose (2-DG), 1 mM alpha-cyano 4-hydroxy cinnamate (4-CIN) or 10 mM D-glucose. The response of parameters assessed (metabolite levels and enzyme activities) provided evidence for some characteristics of lactate metabolism in fish liver that were not present when specific inhibitors were used. The main in vivo effects of lactate treatment were increased levels of lactate (approx. 100% increase) and glucose (30-70%) in plasma, as well as decreased glycogen (50%) and lactate (30%) levels, and increased gluconeogenic (20%) and glycolytic (50%) potentials in liver. Those actions, however, were probably the result of an indirect action with other substrates (glucose) and/or hormones since in vitro experiments did not provide similar results for those parameters.
本研究的目的是在虹鳟鱼中获取乳酸在肝脏碳水化合物代谢中作用的证据。在第一个实验中，给鱼腹腔注射（n = 8）5 mL·kg⁻¹的单纯科特兰生理盐水（对照）或含L-(+)-乳酸（22.5 mg·kg⁻¹或45 mg·kg⁻¹）的生理盐水，处理6小时后采集样本。在第二个实验中，为了将乳酸水平升高的单独作用与乳酸水平升高与除葡萄糖以外的激素和代谢物的体内可能相互作用的影响区分开来，将小的肝组织块在含有2、4或8 mM L-(+)-乳酸的改良汉克斯培养基中于15℃体外孵育1小时，单独（对照）或加入50 mM草氨酸盐、1 mM二异丙基氟磷酸（DIDS）、1 mM二氯乙酸（DCA））、10 mM 2-脱氧葡萄糖（2-DG）、1 mM α-氰基-4-羟基肉桂酸（4-CIN）或10 mM D-葡萄糖。所评估参数（代谢物水平和酶活性）的反应为鱼肝中乳酸代谢的一些特征提供了证据，而使用特定抑制剂时这些特征并不存在。乳酸处理的主要体内效应是血浆中乳酸水平（约增加100%）和葡萄糖水平（增加30 - 70%）升高，以及肝脏中糖原水平（降低50%）和乳酸水平（降低30%）降低，糖异生（增加20%）和糖酵解（增加50%）潜力增加。然而，这些作用可能是与其他底物（葡萄糖）和/或激素间接作用的结果，因为体外实验对这些参数未提供类似结果。
