ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06907.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06908.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Catecholamine synthesis in synaptosomal preparations of rat striatum, cortex and brain stem was investigated. The striatum had much higher activity than either the cortex or brain stem. Equilibration of labelled tyrosine between tissue and incubation medium was completed within 2 min. The apparentKmof tyrosine hydroxylase (EC 1.14.3a) and of the overall catecholamine synthetic pathway were both approximately 5 ± 10−6mfor tyrosine. The following amines were found to inhibit striatal dopamine synthesis: dopamine, 25% inhibition at 5 ± 10−7m; noradrenaline, 25% inhibition at 5 ± 10−6m;and serotonin, 30% inhibition at 10−5m. The catecholamine‐induced inhibition of synthesis was antagonized by pre‐incubation with cocaine. Increasing the potassium concentration from 5 to 55 mmcaused a release of amines into the medium which was accompanied by a 40% increase in dopamine synthesis, when synthesis was measured during the first 5 min of exposure to elevated potassium. These results indicate that synaptosomal catecholamine synthesis is inhibited by increases in intra‐synaptosomal amine levels, and that short‐term exposure to depolarizing concentrations of potassium ca

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06909.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The effect of acute hypercapnia upon the energy state of the brain in sustained hyperammonaemia was evaluated in lightly (N2O) anaesthetized rats. No significant changes occurred in the high energy phosphates (phosphocreatine, ATP, ADP, and AMP) despite a fourfold increase in the ammonia content and a 50 per cent reduction in the total α‐ketoglutarate content. It is concluded that brain tissue maintains energy homeostasis in hypercapnic hyperammona

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06910.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Adult rats were denied food for 7 days. As compared with a control group, this severe starvation reduced the mean total body weight by 44 per cent, the weight of the diaphragm by 33 per cent and liver by 67 per cent, the total lipid content of the diaphragm by 57 per cent and liver by 69 per cent, and the total lipid phosphorus content of the diaphragm by 19 per cent and liver by 68 per cent. The decrease in lipid phosphorus contents indicates that the diaphragm and liver catabolized membrane phospholipids as well as triglycerides. In contrast, the fresh weight of the brain and the total lipid content of the brain were not significantly altered by starvation. The fatty acid patterns of the total lipid of the diaphragm and liver (determined by GLC) were grossly altered by starvation. In the brain, however, 17 of the 21 fatty acids measured did not change significantly (P>0.05) and the remaining four changed, with borderline statistical significance, by only 2 to 13 per cent. There was no significant effect of starvation of the pattern of the brain polyunsaturated fatty acids when measured by alkali isomerization. In contrast to the liver and diaphragm, the brain is apparently unable to utilize its lipids appreciably as an energy source. Presumably the lipids of the brain are preserved to permit this organ to function properly, even in the last stages of starvatio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06911.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The influence of general anaesthesia upon the metabolic state of the brain was evaluated from the tissue concentrations of ATP, ADP and AMP, and from the concentrations of glycolytic and citric acid cycle intermediates, in immobilized and artificially ventilated rats anaesthetized either with 70% N2O, 1% halothane or 60 mg/kg of pentobarbitone. The results were compared to the results obtained on awake animals in fentanyl‐analgesia. The adenylate energy charge was identical in all groups studied and there were no H+‐independent changes in the phosphocreatine/creatine ratios. In pentobarbitone anaesthesia there was an accumulation of glucose 6‐phosphate and a fall in fructose 1,6‐diphosphate, indicating inhibition of phosphofructokinase. No significant changes in these metabolites were observed with halothane or nitrous oxide anaesthesia and the substrate patterns differed from that obtained with pentobarbitone.The blood glucose concentrations were higher in the unanaesthetized, immobilized rats given fentanyl than in those anaesthetized. There was a direct relationship between the glucose concentrations in blood and in tissue. The glucose concentration ratios intracellular water to blood were higher in the anaesthetized than in the unanaesthetized animals, increasing with increasing depth of anaesthesia. The intracellular lactate concentrations were lowest in the groups given pentobarbitone and fentanyl citrate, and there was thus no direct relationship between lactate concentration and depth of an

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06912.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—We have examined the subcellular localization of histamine, histamine methyltransferase (EC 2.1.1.8) (HMT) and histidine decarboxylase (EC 4.1.1.22) in rat hypothalamus after osmotic lysis of synaptosome‐containing primary particulate fractions. When crude mitochondrial fractions are subjected to osmotic lysis, histamine is retained within particulate structures, while HMT is released into the supernatant fluid. The majority of histidine decarboxylase activity is also recovered in the supernatant fluid, although more histidine decarboxylase than HMT is retained in particulate fractions. After sucrose gradient fractionation of osmotically lysed crude mitochondrial or microsomal pellets, histamine is also retained in particulate structures, with the greatest amount occurring in a fraction enriched in synaptic vesicles. In these sucrose gradients histidine decarboxylase activity shows a greater particulate localization than does HMT activ

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06913.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Triton‐solubilized acetylcholinesterase (EC 3.1.1.7) of rat brain was submitted to vertical flatbed polyacrylamide gel electrophoresis. Three anodally migrating isoenzyme zones with low relative mobilities could be resolved, each of which on quantitative densitometry appeared to consist of more than one subzone. More than 50 per cent of the total AChE activity was exhibited by the isoenzyme zone closest to the origin (isoenzyme zone 3).Regional differences in AChE isoenzyme activity were quantitative only with the caudate‐putamen complex, midbrain, pons and medulla oblongata exhibiting relatively high content of the three isoenzymes and the cerebral cortex and olfactory bulb possessing weak isoenzyme activities. Intermediate levels of isoenzyme activities were observed in the cerebellum and hippocampus. In all areas examined, the relative percentage values for each isoenzyme remained constant. AChE isoenzymes from the forebrain, brain stem and cerebellum of 15‐ and 30‐day‐old rats appeared to have identical patterns. In brain stem, no quantitative differences could be detected in the isoenzyme activities between 15 and 30 days of age. At both ages, the isoenzymes of male and female rats did not show any qualitative differences.The single cholinesterase (EC 3.1.1.8) isoenzyme which could be identified in brain stem supernatants of 30‐day‐old rats was weakly reactive and appeared to have the same relative mobility as the major acetylcholinesterase zone, zone 3.Acetylcholinesterase isoenzymes failed to demonstrate any differential response toward varying concentrations of inhibitors and to changes in pH. While there were basic similarities in the acetylcholinesterase and cholinesterase isoenzyme patterns of brain, serum, liver, skeletal muscle and intestine, brain alone exhibited a marked preponderance of the acetylcholinesterase i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06914.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Squid axonal preparations consisting of the giant axon plus adhering small nerve fibres were incubated for 30 min with phospholipase A (1, 0.2 and 0.025 mg/ml); phospholipase C (10 and 0.5 mg/ml) or lysolecithin (1 and 0.2 mg/ml) followed by another 30 min incubation in normal sea water. The axoplasm and envelope (sheath) of the axonal preparation were then separated and the phospholipids and free amino acids determined. The released amino acids were also measured in the incubation solutions. Compared to phospholipase C, phospholipase A caused a much greater reduction in the free amino acid content of axoplasm and envelope; and a concomitant much greater increase in amino acids released into the incubation solutions, even when phospholipase A was used in concentrations which caused less phospholipid splitting than phospholipase C. Lysolecithin had a much weaker effect than phospholipase A. It is concluded that disruption of hydrophobic binding has a much greater effect on the structure of the non‐lipid portion of the axonal membranes than does disruption of hydrophilic (electrostatic) forces of interaction. Our results can be interpreted in terms of the protein‐crystal or mosaic models of membrane structure whereas they do not support the unit membrane hypot

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06915.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—1Chromatin protein fractions were separated from the nuclei from brain, liver and kidney of the guinea pig. The fractions were studied by electrophoretic methods and amino acid analysis.2Brain nuclear fractions were washed with 0.15m‐NaCl and nuclear acidic proteins then removed by 0.35m‐NaCl. These 0.35m‐NaCl‐extracted proteins were considered to be similar to the nuclear soluble acidic proteins.3Nonhistone‐1, histone and nonhistone‐2 fractions were obtained from 2.0m‐NaCl‐soluble chromatin fractions by lowering the salt concentration and successive extraction with acid and alkali. The nonhistone‐3 fraction was also extracted from the nuclear residue by alkaline solution.4The contents and characteristics of the nonhistone fractions of the brain, especially the nonhistone‐1 fraction, differed among the three tissues. The histone fractions showed no obvious difference among the three tissues. The nonhistone‐1 fraction of the brain, which comprised a low percentage of total nuclear protein, contained relatively high amo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb06916.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY