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Summary Thel-alanine-dependent transport of sodium ions across the plasma membrane of rat-liver parenchymal cells was studied using isolated plasma membrane vesicles. Sodium uptake is stimulated specifically by thel-isomer of alanine and other amino acids, whose transport is sodium-dependent in rat-liver plasma membrane vesicles. Thel-alanine-dependent sodium flux across the membrane is inhibited by an excess of Li+ ions, but not by K+ or choline ions. Sodium transport is sensitive to-SH reagents and ionophores, and is an electrogenic process: a membrane potential (negative inside) can enhancel-alanine-dependent sodium accumulation. The data presented provide further evidence for a sodium-alanine cotransport mechanism. 相似文献
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A G Palekar J A Canas S S Kalbag S J Kim M Castro-Magana M A Angulo 《Biochemical medicine and metabolic biology》1989,41(1):64-69
The intraperitoneal administration of L-norvaline and L-methionine-SR-sulfoximine to rats caused an increase in the concentration of ammonia in plasma as well as in liver. These compounds interfere with urea and glutamine formation, respectively. Subsequent injection of sodium benzoate failed to alleviate ammonia levels, and on the contrary, caused a further increase. Sodium benzoate itself, when administered, resulted in higher levels of ammonia in plasma and liver of the rats. Administration of glycine to rats treated with benzoate did not lower ammonia levels indicating that other factors besides glycine may also be necessary for the removal of sodium benzoate. 相似文献
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Summary Amino acids antioxidant capacity has been investigated and compared with the chain-breaking antioxidant activity of known compounds as ascorbic acid and Trolox. Basic and acidic amino acids and most of neutral ones showed no antioxidant capacity. On the contrary, tryptophan, tyrosine, cysteine and homocysteine showed antioxidant ability at concentrations which are within the usually reported physiological ranges.These findings are discussed in connection with the antioxidant capacity ascribed to plasma proteins, as human serum albumin. 相似文献
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Translocation of some anions cations and acids in rat liver mitochondria 总被引:38,自引:0,他引:38
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González-Hernández JC Aguilera-Aguirre L Pérez-Vázquez V Ramírez J Clemente-Guerrero M Cortés-Rojo C Saavedra-Molina A 《Amino acids》2003,24(1-2):163-169
Summary. We studied the role of the D-amino acids (D-aa) D-serine, D-alanine, D-methionine, D-aspartate, D-tyrosine and D-arginine
on rat liver mitochondria. The stability of D-amino acids, mitochondrial swelling, transmembrane potential and oxygen consumption
were studied under oxidative stress conditions in rat liver mitochondria. In the presence of glutamate-malate all D-aas salts
increased mitochondrial swelling, while in the presence of succinate plus rotenone only D-ala, D-arg and D-ser, induced mitochondrial
swelling. The transmembrane potential (ΔΨ) was decreased in the presence of 1 μM Ca2+. The D-aas inhibited oxygen consumption in state 3. The D-aa studied exerted effects on mitochondria via an increase of free
radicals production.
Received January 15, 2002 Accepted April 14, 2002 Published online September 4, 2002
Acknowledgements The authors appreciated the partial economical support from Mexican grants of CONACYT (to A.S.-M. during its sabbatical)
and CIC-UMSNH (2.5) and critical readings from Rafael álvarez-González.
Authors' address: Alfredo Saavedra-Molina, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo,
Edificio B-3. C.U., Morelia, Mich. 58030. México, Fax: 52-443-326-5788, E-mail: saavedra@zeus.umich.mx 相似文献
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Amino acid transport in plasma membrane vesicles from isolated rat liver parenchymal cells 总被引:1,自引:0,他引:1
Plasma membrane vesicles were prepared from isolated rat liver parenchymal cells. The transport of several amino acids was studied and found to be identical to that in membrane vesicles from whole liver tissue. 相似文献
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Ia Ia Elchiev 《Parazitologiia》1986,20(6):476-479
The amino acid composition of protein in the oocysts of Eimeria tenella has been studied in detail by using the new method of purification of the coccidial oocysts. 35 amino acids and their metabolites have been established for the first time at the exogenous stages of development of E. tenella. The oocyst sporulation is noted to be followed by quantitative changes of the majority of free amino acids and their metabolites. 相似文献
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Uroplakins and cytokeratins in the regenerating rat urothelium after sodium saccharin treatment 总被引:5,自引:2,他引:5
A sodium saccharin (NaSac) diet was used to induce cell damage and regeneration in the urothelium of the male rat urinary
bladder. Foci of terminally differentiated superficial cell exfoliation were detected after 5 weeks and their number increased
after 10 and 15 weeks of the diet. At the sites of superficial cell loss, regenerative simple hyperplasia developed. Within
5 weeks of NaSac removal, regeneration re-established normal differentiated urothelium. In order to follow urothelial differentiation
during regeneration we studied the expression of uroplakins and cytokeratins by means of immunocytochemistry and immunohistochemistry,
respectively. Normal urothelium was characterised by terminally differentiated superficial cells which expressed uroplakins
in their luminal plasma membrane and cytokeratin 20 (CK20) in the cytoplasm. Basal and intermediate cells were CK20 negative
and cytokeratin 17 (CK17) positive. In hyperplastic urothelium all cells synthesised CK17, but not CK20. Differentiation of
the superficial layer was reflected in three successive cell types: cells with microvilli, cells with rounded microridges
and those with a rigid-looking plasma membrane on the luminal surface. The cells with microvilli did not stain with anti-uroplakin
antibody. When the synthesis of uroplakins was detected rounded microridges were formed. With the elevated expression of uroplakins
the luminal plasma membrane becomes rigid-looking which is characteristic of asymmetric unit membrane of terminally differentiated
cells. During differentiation, syn-thesis of CK17 ceased in superficial cells while the synthesis of CK20 started. These results
indicate that during urothelial regeneration after NaSac treatment, specific superficial cell types develop in which the switch
to uroplakin synthesis and transition from CK17 to CK20 synthesis are crucial events for terminal differentiation.
Accepted: 19 August 1997 相似文献
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It has been established that cysts S. fusiformis and S. gigantea of parasites isolated from the esophagi of infected buffaloes and sheep have the identical set of free amino acids and their metabolites. These species differ from each other in 7 components of 34 studied that points to their metabolic closeness and to specific differences of sarcocysts from different hosts. 相似文献
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Mechanisms of autophagic proteolysis in the liver have been studied using vinblastine. Vinblastine stimulated degradation by induced autophagy in a dose-related fashion [1, 2]. Insulin partially inhibits the increased rate of degradation and the formation of autophagosomes as well as the lysosomal fragility induced by vinblastine. Insulin has little effect, however, on basal, non-induced degradation rates. Vinblastine-induced autophagy enhances the degradation of both ‘old’ and ‘newly’ synthesized proteins and is therefore in that sense a random process. The administration of high doses of colchicine also augments proteolysis. This effect is attributed to increase in autophagy. The very nascent vinblastine-induced autophagosomes appear to lack hydrolytic enzymes and acquire them only after fusion with lysosomes. The autophagolysosomal population induced by vinblastine is heterogeneous with respect to shape, size, content and density. Isolated secondary lysosomes (‘residual bodies’) lacking morphologically recognizable sequestered membranes (degradable substrate) show no release of degradation products. Autophagosomes fuse with secretory vesicles originating from the Golgi apparatus. 相似文献