摘要:

Abstract—(1) Cerebral slices were incubated in Ca2+‐free media or in media which contained 2.8 mm‐Ca2+. Omission of Ca2+brought about a drop in creatine phosphate content of 28 per cent, as well as a drop of 3–10 per cent in non‐inulin K+content. There was little change in content of 10‐min phosphate or of non‐inulin Na+.(2) Ouabain in concentrations of to M increased the loss of K+from the slice and caused a rise in Na+content. The changes were most marked in Ca2+‐free media. Creatine phosphate levels were depressed by ouabain both in the presence or absence of Ca2+. In the absence of Ca2+, the lowering of phosphocreatine did not occur until significant shifts in K+had taken place. In contrast, slices incubated in Ca2+‐containing media lost creatine phosphate and K+at about the same rate.(3) When ouabain and labelled phosphate were added simultaneously, there was little difference in the rate of incorporation of label into creatine phosphate in media which differed in Ca2+concentration. However, incorporation ofazP‐labelled phosphate into creatine phosphate was decreased by 30–40 per cent in media which lacked Ca2+when ouabain was added 15 min prior to the labelled phosphate. This change was not observed when the media contained Ca2+.(4) Ouabain did not affect oxidative phosphorylation or respiratory control when added directly to bovine brain mitochondrial preparations.(5) The results suggest that the previously observed depression of respiration brought about by ouabain in Ca2+‐deficient media is not a good indicator of the proportion of the cell's metabolism used for active cation transport. Under these conditions, the inhibition of cation transport is accompanied by a drop in slice content of high‐energy phosphate which may represent a secondary effect of ouabain, or of cytoplasmic alterations brought about by ouabain, on e

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06175.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—A longitudinal study of the maturation of mouse cerebral lysosomal enzymes has been completed. Activity of the enzymes, acid phosphatase (I.U.B. 3.1.3.2),β‐glucuronidase (I.U.B. 3.2.1.31) andβ‐acetylglucosaminidase (I.U.B. 3.2.1.30) was assayed spectrofluorimetrically on portions of supernatant from 0.25 M sucrose homogenates spun at 6 x 103‐min. Activities were obtained in native (free) and Triton X‐100 activated samples (total).The neonatal period was characterized by relatively low free and high total acid phosphatase activities. An abrupt rise in free activity occurred during the period 10–20 days. Discontinuous anion exchange DEAE cellulose chromatography (0.01m‐tris–maleate, pH 6.3) with elution by ascending molarities of NaCl of the Triton X‐100 activated supernatant revealed three major peaks in the adult. A fourth peak, designated as fraction II (‘maturation fraction’) occurred only during the neonatal period, a time also characterized by increased specific activity of fraction I, with no change in fraction IV. The chromatographic fractions were further characterized by optimal pH, ascorbate, fluoride, Cu2+and Fe2+ions.The maturation profiles of total,β‐glucuronidase and total,β‐acetylglucosaminidase differed from each other, and from that of total acid phosphatase. Comparable differences existed in the profiles of the free activities, and the ratio of free:total activity differed for each enzyme at any selected time especially during the neonatal period. These findings are are discussed with reference to the maturation of isoenzyme fractions with age, and suggest that the changes in structure‐linked organization of individual lysosomal hydrolases are functions of heterogeneity in enzyme com

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06176.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The ribosome–polysome equilibrium of rabbit cerebral cortex is considerably modified after elicitation of epileptic seizures by means of electroshock. Under this condition the number of free ribosomes increases approximately 80 per cent at the expense of a comparable decrease in the polysomal populat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06177.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Of the lipid metabolic changes in Wallerian degeneration, the decomposition of phosphatides was studied in the early stages, 2–14 days after the nerve had been cut. It was found that the decomposition of phosphatides begins only 6 days after section. The amounts of lipid‐P and fatty acid ester decrease in parallel. However, a greatcr decrease in the amount of fatty aldehyde was observed than of the lipid‐P and fatty acid ester; this indicates that the vinyl ether bonds of glycerophosphatides are more sensitive to the degenerative process than the fatty acid ester or phosphorus.The fatty acid ester: lipid‐P ratio, calculated from the results, does not change; however, the fatty aldehyde: lipid‐P ratio shows a marked decrease during this same period. The values of the ratios indicate that in the 2nd week following nerve section, decomposition of glycerophosphatides containing fatty aldehyde (i.e. plasmalogens), in contrast to glycerophosphatides of diacyl form, may be only partial. Thus, in the 2nd week of Wallerian degeneration the formation of lysophosphatides may be presumed to come from the p

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06178.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—During an extensive decomposition of phospholipids, at the end of the second week of Wallerian degeneration, the decomposition of glycerophosphatides were studied in detail. In a degenerative process lasting for 2 weeks about one‐third of the choline phosphatides, two‐thirds of the ethanolamine phosphatides, one‐third of the serine phosphatides and one‐quarter of the inositol phosphatides, were destroyed.The amount of lysophosphatidylcholine decreased proportionally to the destruction of choline phosphatide. On the other hand, the amount of lysophosphatides formed from‘kephalin'‐containing fatty aldehyde, during the marked destruction of these phospholipids, remained constant or increased to a small extent and its percentage distribution increased 2 or 3 times compared with other phospholipids. Ethanolamine phosphatides having a high fatty aldehyde content can be regarded as mainly responsible for the relative accumulation of lys

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06179.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) At least four distinct molecular forms of 4‐aminobutyrate: 2‐oxoglutarate aminotransferase from mouse and rat brain, have been separated by electrophoresis on paper, cellogel, agargel, silicagel and by immunoelectrophoresis.(2) The existence of specific typical electrophoretic profiles in mitochondrial and extramitochondrial compartments was shown.(3) A differential effect of pH on the anionic and cationic 4‐aminobutyrate:2‐oxoglutarate aminotransferase transaminase activities has been shown.(4) The possible consequences of the 4‐aminobutyrate: 2‐oxoglutarate aminotransferase isozyme compartimentation on the local availability of γ‐aminobutyric acid pools ha

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06180.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—1. The effect of pentamethylene tetrazole (PTZ) or metrazol on rat brain phosphorylase (E.C.2.4.1.1.) was studiedin vitro.The inhibitory action of PTZ was dependent on its concentration, being most marked in about 4 mM concentration. The inhibitory effect could be reversed to a great extent by inclusion of 5’AMP in the preincubation mixture. GMP, UMP and pyridoxal phosphate had no protective action under similar conditions.2. PTZ did not appear to be a general inhibitor of enzymes. It had no effect on the activity of rat brain guanine deaminase, E. coli RNA‐polymerase, orE. coliaspartate kinase. The inhibition of rat liver phosphorylase activity by PTZ was of a lower order (20 per cent) in comparison with that of brain phosphorylase (56 per cent).3. Megimide, another convulsant drug, also inhibited the brain phosphorylasein vitro, but the effect of Nikethamide was not so pronounced. Pentothal sodium (a sedative drug) had very little effect on the brain phosphorylase act

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06181.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) ATP: creatine phosphotransferase of rat cerebral cortex is soluble to the extent of 57 per cent when the tissue is homogenized in 0.25 M‐sucrose and 80 per cent when distilled water is used for tissue dispersion. Among particulate fractions, the crude mitochondria] fraction contains the highest percentage of enzyme activity.(2) Discontinuous sucrose gradient fractionation of the crude mitochondrial fraction yields about 55 per cent of the particulate activity in the nerve ending fractions and 24 per cent in the mitochondrial pellet.(3) Rupturing of the nerve‐ending particles by a moderate osmotic shock designed to spare the mitochondria results in about 60 per cent of the ATP:creatine phosphotransferase becoming soluble, the remainder preserving the association with heavy particles, presumably mitochondria.(4) Subfractionation of the microsomal fraction on a discontinuous sucrose gradient reveals that this particulate component of the enzyme is an adsorption artifact.(5) The overall evidence points to at least two distinct subcellular localizations of the enzyme in rat brain cortex, a major soluble component and a particulate component. It has not been unequivocally shown whether the latter, in turn, reflects the presence of a single, mitochondrial component or whether the soluble matrix of the nerve ending particles represents a third locale for the e

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06182.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—By an adaptation of the fluorometric method of Campbelland Moss (1961), the activity of α‐naphthyl acid phosphatase was measured in individual neurons of monkey and human spinal cord and found to be many times higher in nerve cell bodies than in the surrounding neuropil. It was also measured in cerebellar cortex and found most concentrated in the granular (neuronal) layer. As this distribution is distinctive and paralleled by two other acid hydrolases, β‐galactosidase and β‐glucuronidase, it is considered to offer additional support for the lysosomal concept in nervous tissue and to indicate that nerve cell perikarya are much richer in lysosomes than are axons, dendrites or g

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06183.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) Compartmentation of glutamate metabolism in brain cortex previously observed onlyin vivo,has now been demonstratedin vitro.This was shown by using [U‐14C]aspartate and [U‐14C]glutamate as tracer substrates.(2) Preparation and maintenance of the slices at 0° resulted in reversible inhibition of glutamine synthesis. Preincubation at 37° for 10 min or preparation of the slices at room temperature partially overcame this inhibition.(3) Transfer to fresh medium after preincubation had an added stimulatory effect on glutamine synthesis.(4) Incubation in high K+medium (27 mm) altered the relative specific activity of glutamine.(5) The data are in keeping with the postulate of the existence of at least two different pools of citric acid cycle intermediates in the cerebral

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06184.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY