Metabolic Activity Related to the Potassium Pump in the Midgut of Bombyx Mori Larvae
Metabolic Activity Related to the Potassium Pump in the Midgut of Bombyx Mori Larvae
复制标题
家蚕幼虫中肠钾泵相关代谢活动
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
A. Guerritore
中科院分区：
文献类型：
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作者：
P. Parenti;B. Giordana;V. Sacchi;G. Hanozet;A. Guerritore
摘要 家蚕幼虫分离的中肠的跨上皮电位差取决于钾的存在，并且不受灌注介质中添加己糖的影响，而丙氨酸、天冬氨酸、谷氨酸和相应的 2-含氧酸、谷氨酰胺和苹果酸会增强该电位差。中肠酶谱表明三羧酸循环的底物主要由转氨酶的氨基酸代谢提供。因此，氨氧乙酸大大降低了氨基酸刺激的肠跨上皮电位差。对管腔内容物、肠细胞和血淋巴中游离氨基酸浓度的测量表明，谷氨酸、天冬酰胺和谷氨酰胺在细胞中积累，而血淋巴富含碱性氨基酸以及丝素蛋白的主要成分甘氨酸、丙氨酸、丝氨酸和酪氨酸。因此，与三羧酸循环直接相关的氨基酸代谢似乎是家蚕中肠钾泵活动的主要能量来源。
SUMMARY The transepithelial electrical potential difference across the isolated midgut of Bombyx mori larvae is dependent on the presence of potassium and is unaffected by the addition of hexoses to perfusion media, whereas it is enhanced by alanine, aspartic acid, glutamic acid and the corresponding 2oxoacids, glutamine and malate. The midgut enzyme profile indicates that the substrates for the tricarboxylic acid cycle are supplied mainly by amino acid metabolism via transaminases. Accordingly, aminoxyacetate drastically reduces the intestinal transepithelial electrical potential difference stimulated by amino acids. Measurement of the free amino acid concentration in the lumen content, intestinal cells and haemolymph shows that glutamic acid, asparagine and glutamine are accumulated in the cell, whilst the haemolymph is enriched with basic amino acids and with glycine, alanine, serine and tyrosine, the major components of the silk fibroin. Therefore, amino acid metabolism directly related to the tricarboxylic acid cycle seems to be the primary source of energy for the potassium pump activity in B. mori midgut.