Sodium gradient-stimulated transport of L-carnitine into renal brush border membrane vesicles: kinetics, specificity, and regulation by dietary carnitine.
Sodium gradient-stimulated transport of L-carnitine into renal brush border membrane vesicles: kinetics, specificity, and regulation by dietary carnitine.
复制标题
钠梯度刺激左旋肉碱转运至肾刷状缘膜囊泡：动力学、特异性和膳食肉碱的调节。
DOI：
10.1016/0003-9861(84)90212-1
复制
发表时间：
1984
影响因子：
3.9
通讯作者：
Diane L. Mack
中科院分区：
文献类型：
--
作者：
C. Rebouche;Diane L. Mack
l-Carnitine transport by rat renal brush border membrane vesicles was stimulated by a Na+gradient (extravesicular > intravesicular). Total carnitine entry was 2.7 and 3.2 times higher at 15 s in the presence of a 100 mmNaCl gradient than when the vesicles were incubated isoosmotically in buffered 100 mmKCl or buffered mannitol, respectively. Specific carnitine transport (total entry minus contribution from diffusion) was stimulated 3.6- and 5.7-fold, respectively. An “overshoot” was observed for total carnitine entry in the presence of a Na+gradient but not in the presence of a K+gradient or in the absence of an ion gradient.l-Carnitine transport was saturable.KTandVmaxfor total carnitine transport were 0.11 mmand 11.6 pmol s−1mg protein−1, respectively, and for Na+-gradient-dependent carnitine transport, 0.055 mmand 5.09 pmol s−1mg protein−1, respectively. The transport process was structure-specific for a quaternary nitrogen and carboxyl groups attached by a 4- to 6-carbon chain, but without other charged functional groups. Other evidence for a carrier-mediated process includedtrans-stimulation of transport by intravesicular carnitine and a peak of activity at near physiological temperature. Kinetic data derived from this study, coupled with data from previous physiological studies from this laboratory, suggests that carnitine transport by the brush border membrane is not limiting for carnitine reabsorption. Dietary carnitine (1% of diet for 10 days) reduced by 52% the rate of carnitine transport across the brush border membranein vitro, without affecting rates ofd-glucose,l-lysine,l-glutamic acid, orl-alanine transport. Down-regulation of carnitine transport may prevent excessive or toxic accumulation ofl-carnitine in renal tubular cells exposed to high extracellular carnitine concentrations.
肾γ-丁甜菜碱羟化酶对人体肉毒碱生物合成的意义。
DOI：
--
发表时间：
1980
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Rebouche,CJ;Engel,AG
通讯作者：
Engel,AG