共查询到20条相似文献,搜索用时 31 毫秒
1.
J. Diez P. Braquet R. Verna C. Nazaret R. P. Garay 《Cellular and molecular life sciences : CMLS》1985,41(5):666-667
Summary Exogenous cyclic AMP (cAMP) inhibits the Na+, K+-cotransport system and stimulates the Na+, K+-pump and Na+, Ca2+ exchange in mouse macrophages. These effects are enhanced by inhibition of phosphodiesterase with methylisobutylxanthine (MIX). MIX alone showed little or no effect. A similar response was observed after stimulation of endogenous production of cAMP by isoproterenol. 相似文献
2.
J. -F. Cloix G. Dagher M. Crabos M. -G. Pernollet P. Meyer 《Cellular and molecular life sciences : CMLS》1984,40(12):1380-1382
Summary Na+, K+-ATPase inhibitors extracted from plasma of healthy human subjects displaced3H-ouabain binding to human erythrocytes and inhibited the Na+ efflux catalyzed by the Na+, K+-pump and unexpectedly the Na+, K+-cotransport system without alteration of the Na+, Na+-exchange or the Na+ passive permeability. This suggests the presence in healthy human plasma of endogenous factors with ouabain-like and furosemide-like activities.Acknowledgments. We are indebted to Dr M. A. Devynck for her advice on chemical measurements and to Dr R. P. Garay for his help with flux measurements 相似文献
3.
D. Chao G. Balboni L. H. Lazarus S. Salvadori Y. Xia 《Cellular and molecular life sciences : CMLS》2009,66(6):1105-1115
Activation of δ-opioid receptors (DOR) attenuates anoxic K+ leakage and protects cortical neurons from anoxic insults by inhibiting Na+ influx. It is unknown, however, which pathway(s) that mediates the Na+ influx is the target of DOR signal. In the present work, we found that, in the cortex, (1) DOR protection was largely dependent
on the inhibition of anoxic Na+ influxes mediated by voltage-gated Na+ channels; (2) DOR activation inhibited Na+ influx mediated by ionotropic glutamate N-methyl-D-aspartate (NMDA) receptors, but not that by non-NMDA receptors, although both played a role in anoxic K+ derangement; and (3) DOR activation had little effect on Na+/Ca2+ exchanger-based response to anoxia. We conclude that DOR activation attenuates anoxic K+ derangement by restricting Na+ influx mediated by Na+ channels and NMDA receptors, and that non-NMDA receptors and Na+/Ca2+ exchangers, although involved in anoxic K+ derangement in certain degrees, are less likely the targets of DOR signal.
Received 26 November 2008; received after revision 26 December 2008; accepted 13 January 2009 相似文献
4.
Summary Araplysillins-I and-II, two novel dibromotyrosine derivatives, were isolated fromPsammaplysilla arabica and their structure was elucidated by spectroscopic methods. They proved to be inhibitors of Na+/K+ ATPase and to have antimicrobial activity. 相似文献
5.
Sampaio MS Bezerra IP Peçanha FL Fonseca PH Capella MA Lopes AG 《Cellular and molecular life sciences : CMLS》2008,65(19):3093-3099
The lack of Na+,K+-ATPase expression in intercalated cells (IC) is an intriguing condition due to its fundamental role in cellular homeostasis.
In order to better understand this question we compared the activities of Na+,K+-ATPase and Na+-ATPase in two MDCK cell clones: the C11, with IC characteristics, and the C7, with principal cells (PC) characteristics.
The Na+,K+-ATPase activity found in C11 cells is far lower than in C7 cells and the expression of its β-subunit is similar in both cells.
On the other hand, a subset of C11 without α-subunit expression has been found. In C11 cells the Na+-ATPase activity is higher than that of the Na+,K+-ATPase, and it is increased by medium alkalinization, suggesting that it could account for the cellular Na+-homeostasis. Although further studies are necessary for a better understanding of these findings, the presence of Na+-ATPase may explain the adequate survival of cells that lack Na+,K+-ATPase.
Received 09 July 2008; received after revision 03 August 2008; accepted 12 August 2008 相似文献
6.
K. Yamada A. Goto M. Ishii M. Yoshioka T. Sugimoto 《Cellular and molecular life sciences : CMLS》1990,46(10):1041-1043
Summary The effects of adrenalectomy or nephrectomy, carried out one hour previously, on the levels of endogenous digitalis-like factors were determined in rat plasma. Factors were assayed by digoxin-like immunoreactivity and direct Na+, K+-ATPase inhibitory activity. Digoxin-like immunoreactivity significantly decreased one hour after bilateral ablation of adrenals, while Na+, K+-ATPase inhibitory activity remained unaltered. There were no changes in either activity one hour after bilateral nephrectomy. These results suggest that digoxin-like immunoreactivity may be derived from the adrenal gland or under adrenal control and the major substances detected by digoxin-like immunoreactivity and direct Na+, K+-ATPase inhibitory activity may be different. 相似文献
7.
Summary There is a difference in phospholipid composition of cardiac (Na++K+)-ATPase preparations between species which are sensitive to ouabain and those which are not. Sphingomyelin is higher and phosphatidylcholine is lower in the enzymes from sensitive species than in those from insensitive ones. Lysophosphatidylcholine is detectable only in the latter preparations. 相似文献
8.
A. J. Peacock 《Cellular and molecular life sciences : CMLS》1985,41(11):1438-1440
Summary (Na++K+)-ATPase activity was higher in preparations from the ileum ofGlossina mortisans than in those from the rectum. This result suggests that the ileum as well as the rectum, may play a role in osmoregulation in the tsetse fly. 相似文献
9.
Summary The accumulation of non-metabolized choline in isolated rat hepatocytes is concentrative in Na+ medium, whereas the accumulation does not exceed unity in a Li+ medium. Ouabain and 2,4-dinitrophenol inhibited the choline uptake. These results indicate that choline is taken up by rat hepatocytes via a Na+-and energy-dependent process, and choline oxidase is not directly connected with the choline transport system. 相似文献
10.
Cytotoxic (CD8+) and helper (CD4+) T cells play a crucial role in resolving infections by intracellular pathogens. The development of technologies to visualize
antigen-specific T cell responses in mice and men over the past decade has allowed a dissection of the formation of adaptive
T cell immunity. This review gives a brief overview of the currently used detection techniques and possible future additions.
Furthermore, we discuss our current understanding of the formation of antigen-specific T cell responses, with particular attention
to the similarities and differences in CD4+ and CD8+ T cell responses, the functional heterogeneity within responder T cell pools and the regulation of CD8+ T cell responses by dendritic cells and CD4+ helper T cells.
Received 16 June 2005; received after revision 2 August 2005; accepted 15 August 2005 相似文献
11.
The mechanisms of HCO
3
–
and Cl– transport across basolateral membranes from rat ileum were investigated in isolated vesicles by means of uptake experiments. Neither Cl–/HCO
3
–
exchanger nor Na+–(HCO
3
–
)n cotransport seem to be present in ileal basolateral membranes. Moreover Cl– uptake is unaffected bycis Na+ and/or K+ gradients, indicating the absence of Na+–Cl–, K+–Cl– and Na+–K+–2Cl– symport activity. An electrically conductive pathway seems to be responsible for both HCO
3
–
and Cl– fluxes. Evidence is also given for the presence of a Na+/H+ exchanger at the basolateral pole of ileal enterocytes. 相似文献
12.
In isolated goldfish hepatocytes underaerobic conditions the energy requirement for the sodium pump (calculated from Rb+ flux) is closely matched by the ouabain-sensitive fraction of oxygen consumption, whereas during in vitroanoxia (cyanide inhibition of the electron transport chain) the measured ATP demand of the sodium pump clearly exceeds ouabain-sensitive ATP production by anaerobic glycolysis. We conclude that when the energy status of cells is low, part or all of the ATP spared by the inhibition of a particular function may be used for fuelling other ATP-consuming functions. 相似文献
13.
Action of juvenile hormone on the follicle cells ofRhodnius prolixus: Evidence for a novel regulatory mechanism involving protein kinase C 总被引:1,自引:0,他引:1
Summary Juvenile hormone (JH) is known to act on the membranes of the follicle cells ofRhodnius, activating a specific Na+, K+-ATPase. This leads to a decrease in volume of the cells and the appearance of spaces between them (patency). The addition of an inhibitor of protein kinase C, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), to the medium in vitro inhibits the action of JH on the follicle cells. PDBU (phorbol-12,13-dibutyrate) mimics the action of JH in vitro and the response of the follicle cells to, PDBU is blocked by ouabain. It is concluded that the activation of protein kinase C is a required step in the chain of events leading to activation of the JH-dependent ATPase and set in train by the binding of JH to the membrane. 相似文献
14.
A. A. Shaheen A. A. Abd El-Fattah M. Z. Gad 《Cellular and molecular life sciences : CMLS》1996,52(4):336-339
The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na+, K+-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO2) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipidj peroxide formation in braini as indicated by an increase in the level of MDA, being higher after starvation than hypoxia. Brain SOD activity was also increased in response to hypoxia and starvation while GSH content was only diminished ini hypoxia. However, neither MDA nor antioxidants were affected by immobilization. On the other hand, the activity of brain Na+, K+-ATPase was significantly increased by immobilization and hypoxia but decreased in starvation. A similar pattern of change was also observed in plasma glucose and corticosterone levels in response to these stressors. These results elucidate differences in the biochemical response of animals towards various types of stress, with increased lipid peroxide formation in hypoxia and starvation. 相似文献
15.
D. D. Fanestil 《Cellular and molecular life sciences : CMLS》1980,36(9):1045-1046
Summary In the isolated urinary bladder of the toad, 10–5–10–4M orthovanadate produces inhibition of the active transport of Na+ and H+ ions as well as of antidiuretic hormone-mediated osmotic flow of water. Since transport of H+ ions and osmotic water flow are not inhibited when (Na++K+)-ATPase is inhibited by ouabain, biological actions of vanadate are not necessarily related to inhibition of (Na++K+)-ATPase.This research was supported by grant AM-14915 from the National Institutes of Helath. 相似文献
16.
Mari SA Soragna A Castagna M Bossi E Peres A Sacchi VF 《Cellular and molecular life sciences : CMLS》2004,61(2):243-256
To investigate the peculiar ionic specificity of KAAT1, an Na+- and K+-coupled amino acid cotransporter from Lepidoptera, a detailed analysis of membrane topology predictions was performed, together with sequence comparison with strictly Na+-dependent mammalian cotransporters from the same family. The analysis identified aspartate 338, a residue present also in the other cotransporter accepting K+ (CAATCH1), but absent in most mammalian transporters that have, instead, an asparagine in the corresponding position. Mutation of D338 in KAAT1 led either to non-functional transporters (D338G, D338C), or to an altered ionic selectivity (D338E, D338N), observable in uptake experiments and in electrophysiological properties. In particular, in D338E, the transport activity, while persisting in the presence of Na+, appeared to be completely abolished in the presence of K+. D338E also showed uncoupling between transport-associated current and uptake. The opposite mutation in the -aminobutyric acid transporter rGAT-1 (N327D) resulted in complete loss of function. In conclusion, aspartate 338 in KAAT1 appears to be important in allowing K+, in addition to Na+, to drive the transport mechanism, although other residues in different parts of the protein may also play a role in the complete determination of ionic selectivity.Received 23 September 2003; received after revision 11 November 2003; accepted 25 November 2003 相似文献
17.
M. A. Chuman C. L. Schauf F. A. Davis D. Stefoski 《Cellular and molecular life sciences : CMLS》1987,43(2):169-171
Summary The K+ conductance inMyxicola giant axons activates in two phases which are pharmacologically separable. The fast phase of K+ activation is specifically inhibited by 4-aminopyridine and by the substitution of D2O for H2O. We suggestMyxicola giant axons, like the amphibian node of Ranvier, may possess more than one variety of K+ channel. 相似文献
18.
C. M. Vázquez R. Coleto R. Zanetti V. Ruiz-Gutierrez 《Cellular and molecular life sciences : CMLS》1997,53(5):442-446
In the present study, we have examined the intestinal Na+ transport, through the Na+-H+ exchanger, in ileal brush-border membrane vesicles (BBMV) isolated from spontaneously hypertensive rats (SHR), and normotensive
Wistar Kyoto (WKY) rats as a control group. Na+ uptake into ileal BBMV was stimulated in the presence of a proton gradient (pH 5.5 inside/pH 7.5 outside) in SHR and WKY
rats, resulting in a transient accumulation (overshoot) in both groups of rats. No overshoot was observed in the absence of
a pH gradient. The magnitude of the accumulation was significantly higher in SHR than in WKY rats. Uptake of Na+ at equilibrium was identical in the presence and the absence of a proton gradient and was not changed in SHR. The use of
amiloride inhibited pH gradient-driven Na+ uptake in a dose-dependent manner with a Ki of 90 μM and 100 μM for SHR and WKY rats, respectively. The relationship between
proton gradient-driven Na+ uptake and external Na+ concentration was saturable and conformed to Michaelis-Menten kinetics in both SHR and WKY rats. Lineweaver-Burk analysis
of the pH gradient-driven Na+ uptake indicated values of Vmax that were significantly increased in SHR compared to WKY rats (11.4±0.55 nmol/mg/8 s vs. 4.96±0.78 nmol/mg/8 s for SHR and
WKY rats, respectively). In contrast, similar Km values for Na+ were found between SHR and WKY rats (4.0±0.2 mM vs. 4.9±0.6 mM for SHR and WKY rats, respectively). These studies show derangement
in ileal BBMV Na+ transport of SHR, which is characterized by increased Na+-H+ exchanger activity.
Received 18 December 1996; received after revision 3 February 1997; accepted 7 February 1997 相似文献
19.
The venoms of predatory cone snails harbor a rich repertoire of peptide toxins that are valuable research tools, but recently
have also proven to be useful drugs. Among the conotoxins with several disulfide bridges, the O-superfamily toxins are characterized
by a conserved cysteine knot pattern: C-C-CC-C-C. While ω-conotoxins and κ-conotoxins block Ca2+ and K+ channels, respectively, the closely related δ- and μO-conotoxins affect voltage-gated Na+ channels (Nav channels). δ-conotoxins mainly remove the fast inactivation of Nav channels and, thus, functionally resemble long-chain scorpion α-toxins. μO-conotoxins are functionally similar to μ-conotoxins,
since they inhibit the ion flow through Nav channels. Recent results from functional and structural assays have gained insight into the underlying molecular mechanisms.
Both types of toxins are voltage-sensor toxins interfering with the voltage-sensor elements of Nav channels.
Received 27 December 2006; received after revision 30 January 2007; accepted 19 February 2007 相似文献
20.
F. Petrelli S. Coderoni P. Moretti M. Paparelli 《Cellular and molecular life sciences : CMLS》1977,33(9):1189-1190
Summary In biotin-deficient rats, a decreased intestinal transport of Na+, H2O and L-phenylalanine, and no transport differences of 3-O-methyl-D-glucose were observed. The lower Na+ and L-phenylalanine transport appears to be referable to a decreased energy availability and probably not to the lack of a carrier. 相似文献