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221.
Enterocytes isolated from rat jejunum were tested for the existence of a Cl–/HCO
3
–
exchange, previously evidenced in basolateral membrane vesicles but not in brush border. Cells were found to retain functional integrity and transport capabilities long enough to allow Cl– fluxes to be measured. Both efflux and uptake experiments indicate that a Cl–/HCO
3
–
antiport, inhibited by 4,4-diisothiocyanostilbene-2-2-disulfonic acid (DIDS), is functional under resting conditions. 相似文献
222.
S. Fujino K. Satoh T. Nakai K. Togashi T. Kado M. Fujino T. Arima M. Fujino 《Cellular and molecular life sciences : CMLS》1993,49(2):138-144
The excitation-contraction (E-C) coupling process in single twitch fibres from frog toe muscle was inhibited selectively by phenylglyoxal (PGO), a specific guanidyl modifying reagent. A new protein (31.5 kDa), which has PGO-binding ability and seems to play a key role in the E-C coupling process, was solubilized from transverse tubule membrane-junctional sarcoplasmic reticulum complexes (TTM-JSR) of frog skeletal muscles, using14C-PGO. The monoclonal antibody against this protein applied extracellularly inhibited the E-C coupling process of the single fibres. This protein appears to constitute the very first step of input for E-C coupling. It is considered to behave as an indispensable part of an electrometer to measure membrane potentials. Therefore, the name electrometrin is suggested for the new protein. 相似文献
223.
J. K. Lanyi 《Cellular and molecular life sciences : CMLS》1993,49(6-7):514-517
The mechanism of proton transport in the light-driven pump bacteriorhodopsin is beginning to be understood. Light causes the all-trans to 13-cis isomerization of the retinal chromophore. This sets off a sequential and directed series of transient decreases in the pKa's of a) the retinal Schiff base, b) an extracellular proton release complex which includes asp-85, and c) a cytoplasmic proton uptake complex which includes asp-96. The timing of these pK changes during the photoreaction cycle causes sequential proton transfers which result in the net movement of a proton across the protein, from the cytoplasmic to the extracellular surface. 相似文献
224.
225.
Lanyi JK 《Experientia》1993,49(6-7):514-517
The mechanism of proton transport in the light-driven pump bacteriorhodopsin is beginning to be understood. Light causes the all-trans to 13-cis isomerization of the retinal chromophore. This sets off a sequential and directed series of transient decreases in the pKa's of a) the retinal Schiff base, b) an extracellular proton release complex which includes asp-85, and c) a cytoplasmic proton uptake complex which includes asp-96. The timing of these pKa changes during the photoreaction cycle causes sequential proton transfers which result in the net movement of a proton across the protein, from the cytoplasmic to the extracellular surface. 相似文献
226.
H. Fujioka K. Horiike M. Takahashi T. Ishida M. Kinoshita M. Nozaki 《Cellular and molecular life sciences : CMLS》1993,49(1):47-50
The vascular effects of 2-mercaptoethanol, cysteamine, L-cysteine, glutathione (GSH), cystamine and oxidized GSH (GSSG) on the isometric tension of isolated dog coronary arterial strips were examined, and these effects were compared with the triphasic response induced by dithiothreitol (DTT); a rapid and weak contraction (phase A), an intervening slow relaxation (phase B) and a slowly-developing strong contraction (phase C) which we previously reported. The responses of the arteries induced by 2-mercaptoethanol, cysteamine and L-cysteine consisted of phases A, B and C. The order of contractile potency (ED50 of phase C) was DTTL-cysteine>2-mercaptoethanolcysteamine, while the order of relaxant potency (ED50 of phase B) was DTT>cysteamine2-mercaptoethanol. GSSG and cystamine mainly produced relaxation, which corresponded to phase B. The phase C contraction was specific to the reduced forms of thiols, except for GSH, which produced only relaxation. The participation of endothelial cells was not essential for the contracting or relaxing effects of the thiol compounds. The phase C contraction was depressed by W-7, a calmodulin antagonist, while phase A was not. Therefore calmodulin-dependent protein kinases may participate in phase C, not in phase A. 相似文献
227.
M. Rizzardini A. Ferraroli D. Dal Fiume L. Cantoni 《Cellular and molecular life sciences : CMLS》1984,40(12):1390-1392
Summary Im male rats hepatic cytochromes b5 and P-450 were reduced at different times after treatment with cyclophosphamide (CP) (200 mg/kg i.p. for 3 days). In contrast, microsomal heme did not change until 48 h after the last dose of CP, leading to accumulation of heme in a non-cytochromal form. Parallel to the above changes the heme metabolism showed derangement: -aminolaevulinate synthase, the rate-limiting enzyme in heme synthesis, was depressed and heme oxygenase, the enzyme which catalyzes the oxidative degradation of heme, was increased. 相似文献
228.
E. A. Morguenstern M. I. Vacas M. I. Keller Sarmiento D. P. Cardinali 《Cellular and molecular life sciences : CMLS》1984,40(2):223-224
Summary Pinealectomy (Px) in adult male rats resulted in increased cyclic AMP accumulation by medial basal hypothalamic (MBH) explants 3 and 7 days after surgery. 24 h after superior cervical ganglionectomy (Gx) an augmented MBH cyclic AMP accumulation was observed. The effects of Px and Gx were additive, as revealed in animals subjected to Gx 3 days after Px.This study was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (No 6638) and from the Fundación Alberto J. Roemmers, Argentina. 相似文献
229.
Ph. van den Bosch de Aguilar Ch. Langhendries-Wéverberg J. Goemaere-Vanneste F. Flament-Durand J. P. Brion A. M. Couck 《Cellular and molecular life sciences : CMLS》1984,40(4):402-403
Summary Senile dementia of the Alzheimer type (SDAT) is a major problem in the human senescent population. As this pathology cannot be reproduced in animals, research into its development is greatly impeded. The technique of implantation of the nervous tissue has been utilized in order to establish an animal model and to test the possible existence of a transmissible agent. When human temporal cortex with Alzheimer's disease is implanted in the occipital cortex of 7-week-old rats, human cerebral tissue containing abundant tangles induces in the receiver cortex a reactive fibrous gliosis. In the processes of the astrocytes, twisted filaments are evident among bundles of normal filaments. These alterations could be induced by the metabolising of abnormal filament subunits or by some infectious agent introduced by the implant.This study is supported by grant No. 2.4517.82 of Fonds de la Recherche Fondamentale Collective of Belgium. 相似文献
230.