摘要:

AbstractWe examined H+and HCO3−transport mechanisms that are involved in the regulation of intracellular pH of Schwann cells. Primary cultures of Schwann cells were prepared from the sciatic nerves of 1–3‐day‐old rats. pHiof single cells attached to cover slips was continuously monitored by measuring the absorbance spectra of the pH‐sensitive dye dimethylcarboxyfluorescein incorporated intracellularly. The average pHiof neonatal Schwann cells bathed in HEPES mammalian solution was 7.17 ± 0.02 (n = 32). In the nominal absence of HCO3−, pHispontaneously recovered from an acute acid load induced by exposing the Schwann cells to 20 mM NH4+(NH4+prepulse). This pHirecovery from the acute acid load was totally inhibited in the absence of external Na+or in the presence of 1 mM amiloride. In both cases, the pHirecovery was readily restored upon readdition of external Na+or removal of amiloride. In the steady‐state, addition of amiloride caused a small and slow decrease in pHiwhich was readily reversed upon removal of amiloride. In the presence of HCO3−, removal of external Cl‐ caused pHito rapidly and reversibly increase by 0.23 = 0.03 (n = 15) and the initial rate of alkalinization was 20.6 ± 2.7 × 10‐4 pH/sec. In the absence of external Na+, removal of bath Cl−still caused pHito increase by 0.15 ± 0.02 and the initial rate of pHiincrease was not significantly altered. In the nominal absence of HCO3−, removal of bath Cl‐ caused pHito increase very slightly (0.05 ± 0.01) with an initial dpHi/dt of only 4.4 ± 0.2 × 10−4pH/sec (n = 4). Addition of 100 μM DIDS did not inhibit the pHiincrease caused by removal of bath Cl−. These data indicate that (1) Rat Schwann cells regulate their pHivia an Na‐H exchange mechanism which is moderately active at steady‐state pHi. (2) In the presence of HCO3−, there is a Na‐independent Cl‐HCO3(base) exchanger which also contributes to regulation of intracellu

ISSN:0894-1491    

DOI:10.1002/glia.440100302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractHuman brain macrophages (microglia) have been isolated from mixed brain cell cultures initiated from explants of neurosurgical adult human tissue in one step according to a method developed for rat microglia. Cells were characterized enzyme‐histochemically (NDPase) in mixed and immunocytochemically (anti‐CD 14) in mixed and isolated cultures. Purified cells were used to investigate in more detail membrane currents by the patch clamp technique. In 14 cells microdialyzed with a standard, K+‐containing intracellular solution there was no indication for a hyperpolarization‐induced K+‐inward current characteristic for newborn rat microglia. However, in 12 cells depo‐larizing pulses initiated a rapidly inactivating inward current which was followed by an outward current (in 4 cells). The outward current appeared to be carried by K+, since it was absent in another 18 cells, recorded by micropipettes containing Cs+instead of K+as the main intracellular cation. The depolarization‐induced inward current persisted un‐der these conditions. This current was inhibited by tetrodotoxin (5μM) and by substitu‐tion of Na+by choline in the bath solution. It is suggested that this Na+‐current is specifically expressed in macrophages derived from adult brain. ©

ISSN:0894-1491    

DOI:10.1002/glia.440100303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractWithin the last few years, the expression of voltage‐dependent, TTX‐sensitive Na+channels has been demonstrated in several types of neuroglial cells such as astrocytes and Schwann cells. Recently, we reported the occurrence of such Na+currents in retinal Müller (glial) cells from dog and cat. This paper deals with the description of the properties of Na+currents in Müller cells isolated from retinae of several mammalian species, as well as from human retinae. These Na+currents were eliminated by TTX (1μM), and by exposure to sodium‐free extracellular solution; typically, they were de‐monstrable only after blocking most of the K+conductance by Ba2+(1 mM). Voltage‐dependent activation and inactivation characteristics and time constants of the Na+currents were similar to those of currents carried by neuronal Na+channels. The esti‐mated number of sodium channels per cell was low (about 1,500 channels per 7,500μm2), and the K+conductance exceeded the peak Na+conductance by an average factor of 5. Thus, the cells were incapable of generating action‐potential‐like responses under cur‐rent clamp. Modelling estimations show that triggering of glial Na+currents under physiological conditions, if any, can at best occur by ephaptic transmission at perinodal sites of optic axons. It is speculated that glial Na+channels might be involved in neuro‐glial signalling events.

ISSN:0894-1491    

DOI:10.1002/glia.440100304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractHuman fetal parietal cortical tissue was transplanted to cortical cavities in immunosuppressed rats. Protoplasmic astrocytes in the human cortical grafts highly expressed human angiotensinogen mRNA as identified with35S‐labeled and digoxigenin‐labeled riboprobes combined with immunohistochemistry for glial fibrillary acidic protein. Antibodies to human specific neurofilament protein 70 KD were used to characterize neurons in the graft and fiber outgrowth into the host brain. Immunohistochemistry revealed human angiotensinogen‐like immunoreactivity in many small protoplasmic astrocytes and very few large neurons. These results demonstrate that human angiotensinogen mRNA and protein is synthesized in immature human glia. We assume that angiotensinogen is transformed into angiotensin peptides, which may participate in the regulation of growth processes. The results suggest that human angiotensinogen may play a role during human ombryogenesis. © 1994 Wiley‐L

ISSN:0894-1491    

DOI:10.1002/glia.440100305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractLectin histochemistry using theGriffonia simplicifolia IIlectin (GSL II) has revealed a novel group of glycoproteins containing terminal N‐acetyl‐D‐glucosamine (GlcNAc) residues in oligodendrocytes. The GlcNAc‐containing glycoproteins were not present in other types of glial cells, but were expressed by some neuronal cell populations. Within oligodendrocytes their localization was confined to the Golgi apparatus, as determined ultrastructurally. Biochemical analyses using tricine/SDS‐polyacrylamide gel electrophoresis and western blotting with GSL II showed the GlcNAc‐containing glycoproteins to be insoluble, with molecular masses ranging from 15 to 30 kDa. Our study provides a first account of insoluble, GlcNAc‐rich 15–30 kDa glycoproteins in oligodendroglia. The findings are discussed in the context of the functional significance of other known oligodendrocyte glycoproteins. © 1994

ISSN:0894-1491    

DOI:10.1002/glia.440100306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe response of neonatal rat oligodendrocytes to contact with myelin extracts prepared from the central and peripheral nervous system was examined. Contact with either CNS myelin or PNS myelin resulted in collapse of the fine structure of the leading edge of oligodendrocytes in vitro. The collapse of the fine structure of oligodendrocyte processes was preceded by a substantial (approximately fivefold) increase in intracellular free calcium concentration. The calcium concentration increase was due, at least in part, to a release of calcium from internal stores, since it persisted when extracellular calcium was removed by chelation with EGTA. The increase in calcium concentration and the coincident morphological change suggest that oligodendrocytes might be able to recognize and react to specific molecules on the surface of other oligodendrocytes. © 1994 Wiley‐Liss, I

ISSN:0894-1491    

DOI:10.1002/glia.440100307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractAs an approach to develop both oligodendrocytic and astrocytic cell lines from adult human spinal cord, a cellular preparation of highly enriched oligodendrocytes and their precursors was infected with a replication‐deficient retrovirus containing DNA sequences encoding the temperature‐sensitive mutant of SV40 large T antigen. Six immortal cell lines were obtained. At both permissive (33°C) and non‐permissive (38.5°C) temperatures, all cell lines were positive for vimentin, two demonstrated glial fibrillary acidic protein (GFAP) immunoreactivity, and none expressed oligodendrocyte or micro‐glial markers. The 2 GFAP‐positive cell lines [human spinal cord (HSC)2 and HSC6] were further characterized. Karyotype analysis revealed that both HSC2 and HSC6 cells showed gain of chromosomal material and structural chromosomal abnormalities. However, at non‐permissive temperature both cell lines were indistinguishable from primary human astrocytes by a number of criteria. These properties included glutamine synthetase activity, Na+‐dependent glutamate uptake, K+flux, purine‐evoked Ca2+mobilization and entry, and the ability to support neurite outgrowth from embryonic rat retinal explants. The HSC2 and HSC6 cell lines may prove to be valuable models for studying the physiological properties of adult human astrocytes. © 19

ISSN:0894-1491    

DOI:10.1002/glia.440100308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe mechanism underlying meningitis‐associated brain injury is unclear. This study investigated the hypothesis that lipopolysaccharide (LPS) alters astrocyte function and structure via the release of proinflammatory cytokines. In enriched murine astrocyte cultures, LPS inhibited (P<0.05) glutamine synthetase activity,3H‐gamma aminobutyric acid uptake, and DNA synthesis; LPS also induced ultrastructural changes. Antibodies to tumor necrosis factor‐α, interleukin‐1, and interleukin‐6 blocked (P<0.05) in part the LPS‐induced inhibition of astrocyte function. Also, treatment of astrocyte cultures with cytokines significantly altered these astrocyte functions and ultrastructure. Taken together, the present findings support the hypothesis that LPS affects astrocyte function and structure via the release of proinflammatory cytokines, especially tumor necrosis factor‐α. © 1994

ISSN:0894-1491    

DOI:10.1002/glia.440100309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440100310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:0894-1491    

DOI:10.1002/glia.440100301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY