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151.
The presence and functional role of the swelling-activated Cl- current (ICl(swell)) in rabbit cardiac Purkinje cells was examined using patch-clamp methodology. Extracellular hypotonicity (210 or 135 mOsm) activated an outwardly rectifying, time-independent current with a reversal potential close to the calculated Cl- equilibrium potential (ECl). The magnitude of this current was related to tonicity of the superfusate. The current was blocked by 0.5 mM 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS). These features are comparable to those of ICl(swell) found in sinoatrial nodal, atrial, and ventricular myocytes. ICl(swell) activation at 210 and 135 mOsm depolarized the resting membrane potential with 6 and 10 mV and shortened the action potential by 18 and 33%, respectively. DIDS partially reversed ICl(swell)-induced action potential changes. We conclude that ICl(swell) is present in Purkinje cells and its activation leads to action potential shortening and resting membrane potential depolarization, both of which can promote the development of reentrant arrhythmias.Received 20 January 2004; received after revision 17 February 2004; accepted 25 February 2004 相似文献
152.
The molecular mechanisms of congenital hypofibrinogenaemia 总被引:7,自引:0,他引:7
Maghzal GJ Brennan SO Homer VM George PM 《Cellular and molecular life sciences : CMLS》2004,61(12):1427-1438
Congenital hypofibrinogenaemia is characterized by abnormally low levels of fibrinogen and is usually caused by heterozygous mutations in the fibrinogen chain genes (, and ). However, it does not usually result in a clinically significant condition unless inherited in a homozygous or compound heterozygous state, where it results in a severe bleeding disorder, afibrinogenaemia. Various protein and expression studies have improved our understanding of how mutations causing hypo- and afibrinogenaemia affect secretion of the mature fibrinogen molecule from the hepatocyte. Some mutations can perturb chain assembly as in the 153 Cys Arg case, while others such as the B Leu Arg and the B414 Gly Ser mutations allow intracellular hexamer assembly but inhibit protein secretion. An interesting group of mutations, such as 284 Gly Arg and 375 Arg Trp, not only cause hypofibrinogenaemia but are also associated with liver disease. The nonexpression of these variant chains in plasma fibrinogen is due to retention in the endoplasmic reticulum, which in turn leads to hypofibrinogenaemia.Received 17 December 2003; received after revision 19 January 2004; accepted 21 January 2004 相似文献
153.
Mignot C Boespflug-Tanguy O Gelot A Dautigny A Pham-Dinh D Rodriguez D 《Cellular and molecular life sciences : CMLS》2004,61(3):369-385
Alexander disease (AXD) is the first primary astrocytic disorder. This encephalopathy is caused by dominant mutations in the glial fibrillary acidic protein (GFAP) gene, encoding the main intermediate filament of astrocyte. Pathologically, this neurodegenerative disease is characterised by dystrophic astrocytes containing intermediate filament aggregates associated with myelin abnormalities.More than 20 GFAP mutations have been reported. Many of them cluster in highly conserved regions between several intermediate filaments. Contrary to other intermediate filament-related diseases, AXD seems to be the consequence of a toxic gain of function induced by aggregates. This is supported by the phenotype of mice overexpressing human GFAP. Nevertheless, GFAP null mice display myelin abnormalities and blood-brain barrier dysfunction that are present in AXD.Given the pivotal role of astrocytes in brain physiology, there are many possibilities for astrocytes to dysfunction and to impair the functions of other cells. Physiopathological hypotheses are discussed in the frame of AXD.Received 11 April 2003; received after revision 22 July 2003; accepted 31 July 2003Both authors contributed equally to this work. 相似文献
154.
What’s new in the renin-angiotensin system? 总被引:6,自引:0,他引:6
Chai SY Fernando R Peck G Ye SY Mendelsohn FA Jenkins TA Albiston AL 《Cellular and molecular life sciences : CMLS》2004,61(21):2728-2737
The angiotensin AT(4) receptor was originally defined as the specific, high-affinity binding site for the hexapeptide angiotensin IV (Ang IV). Subsequently, the peptide LVV-hemorphin 7 was also demonstrated to be a bioactive ligand of the AT(4) receptor. Central administration of Ang IV, its analogues or LVV-hemorphin 7 markedly enhance learning and memory in normal rodents and reverse memory deficits observed in animal models of amnesia. The AT(4) receptor has a broad distribution and is found in a range of tissues, including the adrenal gland, kidney, lung and heart. In the kidney Ang IV increases renal cortical blood flow and decreases Na(+) transport in isolated renal proximal tubules. The AT(4) receptor has recently been identified as the transmembrane enzyme, insulin-regulated membrane aminopeptidase (IRAP). IRAP is a type II integral membrane spanning protein belonging to the M1 family of aminopeptidases and is predominantly found in GLUT4 vesicles in insulin-responsive cells. Three hypotheses for the memory-potentiating effects of the AT(4) receptor/IRAP ligands, Ang IV and LVV-hemorphin 7, are proposed: (i) acting as potent inhibitors of IRAP, they may prolong the action of endogenous promnestic peptides; (ii) they may modulate glucose uptake by modulating trafficking of GLUT4; (iii) IRAP may act as a receptor, transducing the signal initiated by ligand binding to its C-terminal domain to the intracellular domain that interacts with several cytoplasmic proteins. 相似文献
155.
An Hfe-dependent pathway mediates hyposideremia in response to lipopolysaccharide-induced inflammation in mice 总被引:19,自引:0,他引:19
Roy CN Custodio AO de Graaf J Schneider S Akpan I Montross LK Sanchez M Gaudino A Hentze MW Andrews NC Muckenthaler MU 《Nature genetics》2004,36(5):481-485
Inflammation influences iron balance in the whole organism. A common clinical manifestation of these changes is anemia of chronic disease (ACD; also called anemia of inflammation). Inflammation reduces duodenal iron absorption and increases macrophage iron retention, resulting in low serum iron concentrations (hyposideremia). Despite the protection hyposideremia provides against proliferating microorganisms, this 'iron withholding' reduces the iron available to maturing red blood cells and eventually contributes to the development of anemia. Hepcidin antimicrobial peptide (Hamp) is a hepatic defensin-like peptide hormone that inhibits duodenal iron absorption and macrophage iron release. Hamp is part of the type II acute phase response and is thought to have a crucial regulatory role in sequestering iron in the context of ACD. Mice with deficiencies in the hemochromatosis gene product, Hfe, mounted a general inflammatory response after injection of lipopolysaccharide but lacked appropriate Hamp expression and did not develop hyposideremia. These data suggest a previously unidentified role for Hfe in innate immunity and ACD. 相似文献
156.
Jaffe W Meisenheimer K Röttgering HJ Leinert Ch Richichi A Chesneau O Fraix-Burnet D Glazenborg-Kluttig A Granato GL Graser U Heijligers B Köhler R Malbet F Miley GK Paresce F Pel JW Perrin G Przygodda F Schoeller M Sol H Waters LB Weigelt G Woillez J De Zeeuw PT 《Nature》2004,429(6987):47-49
Active galactic nuclei (AGNs) display many energetic phenomena--broad emission lines, X-rays, relativistic jets, radio lobes--originating from matter falling onto a supermassive black hole. It is widely accepted that orientation effects play a major role in explaining the observational appearance of AGNs. Seen from certain directions, circum-nuclear dust clouds would block our view of the central powerhouse. Indirect evidence suggests that the dust clouds form a parsec-sized torus-shaped distribution. This explanation, however, remains unproved, as even the largest telescopes have not been able to resolve the dust structures. Here we report interferometric mid-infrared observations that spatially resolve these structures in the galaxy NGC 1068. The observations reveal warm (320 K) dust in a structure 2.1 parsec thick and 3.4 parsec in diameter, surrounding a smaller hot structure. As such a configuration of dust clouds would collapse in a time much shorter than the active phase of the AGN, this observation requires a continual input of kinetic energy to the cloud system from a source coexistent with the AGN. 相似文献
157.
158.
159.
The importance of extracellular sodium and potassium for acetylcholine-evoked salivary secretion 总被引:1,自引:0,他引:1
O H Petersen 《Experientia》1970,26(10):1103-1104
160.
A. O. Vladutiu 《Cellular and molecular life sciences : CMLS》1981,37(7):778-780
Summary All previous attempts failed to induce thyroglobulin antibodies or thyroid infiltrates in mice immunized with homologous thyroglobulin without adjuvants. However, an allogeneic effect obviated the need of adjuvants for triggering thyroglobulin-reactive lymphocytes to produce thyroglobulin antibodies or thyroid lesions.This work was supported by a grant from the Margaret Duffy and Robert Cameron C. Troup Fund. I thank Ellen Kenney for technical assistance and Dr Pei-nan Tsung for the X-ray irradiation. 相似文献