Rotstein N P, Arias H R, Aveldaño M I, Barrantes F J
Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina.
J Neurochem. 1987 Nov;49(5):1341-7. doi: 10.1111/j.1471-4159.1987.tb00997.x.
The in vivo labeling of electrocyte lipids is followed after injection of radioactive glycerol and two fatty acids, oleate and arachidonate, into the electric organ of an elasmobranch (Discopyge tschudii). De novo synthesis of lipids and acyl-exchange reactions are operative in the electrocyte. The three precursors are preferentially incorporated into phosphatidylcholine, phosphatidylinositol, and triacylglycerols. The highest specific activities are attained by triacylglycerols and polyphosphoinositides. Electrocyte stacks from electric organ show an efficient and continuous esterification of oleate and arachidonate into lipids after several hours of incubation. Except for an apparently more active labeling of triacylglycerols, which is attributed to the larger availability of free fatty acid precursors under the in vitro experimental conditions, the pattern of lipid labeling is similar to that attained in vivo. 32P-labeled lipids are also steadily produced in electrocyte stacks (24 h of incubation with [32P]phosphate) using glucose as the sole exogenous source of energy. Polyphosphoinositides are the lipids preferentially labeled. The ability to sustain the labeling of lipids under in vitro conditions renders isolated electrocyte stacks an interesting model for future research on lipid involvement in cholinergic function.
向一种软骨鱼（Discopyge tschudii）的电器官注射放射性甘油以及两种脂肪酸（油酸和花生四烯酸）后，对电细胞脂质进行体内标记。脂质的从头合成和酰基交换反应在电细胞中起作用。这三种前体优先掺入磷脂酰胆碱、磷脂酰肌醇和三酰甘油中。三酰甘油和多磷酸肌醇具有最高的比活性。在孵育数小时后，来自电器官的电细胞堆叠显示出油酸和花生四烯酸高效且持续地酯化到脂质中。除了三酰甘油的标记明显更活跃（这归因于体外实验条件下游离脂肪酸前体的可用性更高）外，脂质标记模式与体内获得的模式相似。使用葡萄糖作为唯一的外源能量来源，在电细胞堆叠中（用[32P]磷酸盐孵育24小时）也能稳定产生32P标记的脂质。多磷酸肌醇是优先被标记的脂质。在体外条件下维持脂质标记的能力使分离的电细胞堆叠成为未来研究脂质参与胆碱能功能的一个有趣模型。
