SPECIFICITY AND CHARACTERISTICS OF CARNITINE TRANSPORT IN HUMAN HEART-CELLS (CCL 27) IN CULTURE
SPECIFICITY AND CHARACTERISTICS OF CARNITINE TRANSPORT IN HUMAN HEART-CELLS (CCL 27) IN CULTURE
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DOI：
10.1016/0005-2736(77)90257-7
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
EIKLID, K
中科院分区：
文献类型：
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作者：
MOLSTAD, P;BOHMER, T;EIKLID, K
放射性标记左旋肉碱摄取机制的特异性和特征已在培养的人心脏细胞 (CCL 27) 中进行了研究。碘乙酸、2, 4-二硝基苯酚、氧化砷和氰化钾不会显着降低摄取，而高浓度氟化钠 (25-50 mM) 会抑制转运。巯基封闭剂如N-乙基马来酰亚胺、2, 4-二硝基氟苯和Ellman试剂[5, 5-二硫代双-(2-硝基苯甲酸)]都会减少放射性标记肉碱的摄取；而根皮苷 (0.1 mM)、哇巴因或氨基酸 (1–5 mM) 则不然。因此，肉毒碱的转运似乎依赖于游离的巯基，并且与氨基酸或葡萄糖的转运无关，也与(Na++ K+)-ATP酶的活性无关。培养介质中渗透压在 225 至 450 mosM/kg 水之间的变化不会影响吸收。 pH 值从 7 增加到 8 会减少约 10% 的传输。 40%。结构上与肉碱相关的化合物含有三甲氨基和羧基，会减少吸收。左旋肉碱比右旋肉碱与转运机制的结合亲和力更大。具有不同酰基长度的酰基肉碱会抑制转运，且 l 异构体比 d 异构体更能抑制转运。 2μM左旋肉碱摄取的50%抑制浓度为甜菜碱90μM、胆碱11·10 3μM、丁甜菜碱2μM、右旋肉碱20μM、5-三甲氨基戊酸14μM、左旋乙酰肉碱8μM、左旋棕榈酰肉碱3μM。放射性标记的左旋肉碱也以 8 μM 的 K m 和 10 pmol·μ g− 1 DNA· h− 1 的 V 转运到细胞中。左旋肉碱和左旋肉碱之间存在竞争性抑制。由于L-乙酰肉碱占大鼠血浆中肉碱总量的30%，因此L-肉碱和L-乙酰肉碱都可以作为体内这种主动转运机制的生理底物。
The specificity and characteristics of the uptake mechanism for radiolabeled l-carnitine has been studied in cultured human heart cells (CCL 27). Iodoacetate, 2, 4-dinitrophenol, arseneoxide and potassium cyanide do not reduce the uptake significantly, while sodium fluoride in high concentration (25–50 mM) inhibits the transport. Sulfhydryl blocking agents like N-ethylmaleimide, 2, 4-dinitrofluorobenzene and Ellman reagent [5, 5-dithiobis-(2-nitrobenzoic acid)] all reduce the uptake of radiolabeled carnitine; while phloridzin (0.1 mM), ouabain or amino acids (1–5 mM) do not. Thus it seems that the carnitine transport depends upon free sulfhydryl groups, and is neither linked to the transport of amino acids or glucose, nor to the activity of (Na++ K+)-ATPase. Variation in osmolality in the incubation medium within 225 to 450 mosM/kg water does not influence the uptake. An increase in pH from 7 to 8 reduces the transport approx. 40%. Compounds structurally related to carnitine, containing a trimethylamino group and a carboxylic group, reduce the uptake. l-Carnitine has a greater affinity for binding to the transport mechanism than d-carnitine. Acylcarnitines with varying acyl group length inhibit the transport, and the l isomers more than their d counterparts. The 50% inhibiting concentration on the uptake of 2 μM l-carnitine, was 90 μM for betaine, 11· 10 3 μ M for choline, 2 μM for butyrobetaine, 20 μM for d-carnitine, 14 μM for 5-trimethylaminovaleric acid, 8 μM for l-acetylcarnitine and 3 μM for l-palmitoylcarnitine. Radiolabeled l-acetylcarnitine is also transported into the cells with a K m of 8 μM and a V of 10 pmol· μ g− 1 DNA· h− 1. There is a competitive type of inhibition between l-carnitine and l-acetylcarnitine. Since l-acetylcarnitine constitutes 30% of total carnitine in rat plasma, both l-carnitine and l-acetylcarnitine can be physiological substrates for this active transport mechanism in vivo.