摘要:

Abstract—In monkeys we measured the steady‐state concentrations of Cl−in endogenous CSF, in artificial CSF (which had equilibrated with the underlying exposed surface of the cerebral cortex but was not in diffusion equilibrium with endogenous CSF), and in arterial plasma. The ratio of the distribution of Cl−in artificial CSF to that in plasma was consistent with a passive Donnan distribution, whereas that ratio describing Cl−levels in endogenous CSF in comparison to those in plasma clearly exceeded theratio required for a passive, Donnan−type of distribution for Cl−. The kinetic analysis of the efflux of Cl−from blood into endogenous CSF and into artificial CSF (perfused over the exposed surface of the cerebral cortex) indicated that the rate of efflux of Cl−into endogenous CSF which was continuous with ventricular fluid was inhibited by acetazolamide [in confirmation of a similar finding described previously by Marenand Broder(1970)], whereas the rate of efflux of chloride from blood into the artificial CSF perfusate was uninfluenced by pretreatment of animals with acetazolamide. We have discussed the site of mediated (active) transport of chloride from blood into CSF in light

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01448.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The effect of electrical stimulation, tetrodotoxin and cinchocaine (the latter two substances abolish action potentials) on the incorporation of [32P]orthophosphate into the phosphoinositides of isolated rabbit vagus nerve has been studied. Electrical stimulation, or treatment with tetrodotoxin, had little significant effect on the incorporation of [32P]orthophosphate into the phosphoinositides. Cinchocaine, however, caused a 3.5–4.4‐fold increase (P=<0.001) in monophosphoinositide labelling. These findings are discussed in view of the possible function of the phosphoinositides in the nervous s

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01449.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The monoamine oxidases (MAO) of rat pineal gland and superior cervical ganglion were compared and found to have different characteristics. The predominant enzyme in the ganglion was inhibited by low concentrations of clorgyline (0.1 μM), exhibited a lower apparent Kmfor tyramine than the enzyme in the pineal, was readily inactivated by trypsin, and was relatively heat‐stable. In contrast, the MAO of the pineal was inhibited by 0.1 mmclorgyline, was not readily inactivated by trypsin, and was heat‐labile. Moreover, these enzymes appeared to have different substrate specificities. Our results are consistent with the view that there may be multiple forms of MAO and that these forms may be associated with specific cell

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01450.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Cottonmouth moccasin snake venom (SV) was applied to the innervated membrane of the isolated single cell of the Sachs electric organ (electroplax) of the electric eel,Electrophorus electricus. Concentrations as low as 0.05 μg/ml irreversibly antagonized depolarization by carbamylcholine, whereas concentrations of 0.1 mg/ml or higher were required to directly and irreversibly depolarize and block electrical excitation. The active component of the venom was stable to boiling at acid pH, destroyed by boiling at alkaline pH and nondialyzable and corresponded to those fractions containing maximum phospholipaseAactivity demonstrable when isolated by paper electrophoresis and Sephadex filtration. PhospholipaseCand lysolecithin in concentrations of 1 mg/ml and 0.2 mg/ml, respectively, depolarized and blocked electrical excitation, whereas lower concentrations did not antagonize depolarization by carbamylcholine. Triton X‐100 (0.01 mg/ml) antagonized carbamylcholine, whereas 10‐fold higher concentrations directly blocked electrical excitation. Hyaluronidase had no effect on resting or action potential but decreased the depolarizing response to carbamylcholine.At minimal concentrations which blocked the depolarizing response to carbamylcholine, SV caused only slight splitting of phospholipids in single cells of the Sachs organ. A concentration (1 mg/ml) of SV which blocked electrical excitation caused 80–100 per cent splitting of lecithin, phosphatidylethanolamine and phosphatidylserine, the three principal phospholipids of the electric tissue. Similar percentages of splitting of the latter two phospholipids but only about one‐third of the lecithin occurred at SV concentration of 0.1 mg/ml. These results indicate that electrical excitability in the eel electroplax can be maintained in the presence of extensive phospholipid splitting. Depolarization and block of electrical excitation by relatively high concentrations of SV may have resulted from splitting of phospholipids, especially lecithin, or may have reflected action of lysophosphatide detergents produced as a result of the action of phospholipase A upon membranal pho

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01451.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Sympathetic ganglia of the rat and cat were examined for the occurrence and distribution of gangliosides. Each rat superior cervical ganglion contained 0.3 nmol of ganglioside‐sialic acid. Extracts of cat superior cervical and nodose ganglia were chromatographed on silica gel thin‐layer plates. The resulting patterns suggested that similar distributions of multiple forms of gangliosides occur in these two tissues, with the fast‐moving gangliosides predominating. The metabolic activity of gangliosides was also investigated in rat superior cervical gangliain vitro. Evidence was obtained that14C from [U‐14C]glucose, [U‐14C]pyruvate, and [U‐14C]glucosamine was incorporated into the

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01452.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—After isolated rat brain preparations were perfused with fluid containing either mannose or glucose as metabolic substrate, extracts from the rapidly frozen cerebral cortex were prepared and analysed. Brains perfused with mannose contained somewhat lower levels of glucose‐6‐phosphate and fructose diphosphate than those perfused with glucose but the contents of other glycolytic intermediates were quite similar in both groups. The level of mannose‐6‐phosphate was high in brains perfused with either glucose or mannose, but higher in the latter. In both cases, the ratio of mannose‐6‐phosphate to fructose‐6‐phosphate was very high, suggesting that phosphomannose isomerase (EC 5.3.1.8) may be important in the regulation of glycolysis. The levels of adenine nucleotides and creatine phosphate and the redox ratios were not significantly different with mannose as substrate than with glucose. The contents of free amino acids in brains perfused with mannose did not differ significantly from those in brains perfused with glucose. Our results show that mannose is a satisfactory substrate for the brain under these experimental conditions since it maintains the energy reserves and oxidative status of the cerebral tissue and does not alter the leve

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01453.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—The clearance of [14C]leucine from the ventricular and cranial subarachnoid space was studied in cats subjected to ventriculo‐cisternal and ventriculo‐craniosubarachnoidal perfusions. Clearance from both the ventricles and the subarachnoid space was mediated by transport mechanisms with nonsaturable and saturable components. Net clearance from the subarachnoid space was considerably greater than from the ventricles. Analysis of the transport kinetics revealed the affinity constants (Kt) to be comparable for both compartments but transport sites appeared to be more numerous in the subarachnoid space (greaterVmax).Proportionally, the amount of [14C]leucine retained by brain declined as the concentration of leucine in the perfusate was increased. Since at high concentrations the CSF transport systems and presumably cellular uptake were inhibited (self‐saturated) it was assumed that the lower brain levels of [14C]leucine reflected a proportionately greater loss of [14C]‐leucine from the brain interstitial space

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01454.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—A method for the histochemical identification of choline acetyltransferase has been investigated further by studying the effects of certain inhibitors of the enzyme both on rat brain homogenates and on the localization of the enzyme in tissue sections.It was confirmed that acetyl‐CoA hydrolase activity both in homogenates and in tissue sections is inhibited by preincubation in 1 mM‐DFP. The effects of the choline acetyltransferase inhibitors chloro‐ and bromoacetylcholine on the appearance of histochemical staining were related to their activity in homogenates and tissue slices. Bromoketone was found to inhibit choline acetyltransferase in homogenates and, less efficiently, in tissue sections but it also inhibited the hydrolysis of acetyl‐CoA by some other unknown enzyme which is inactivated by 1 mM‐DFP.The results obtained with the choline acetyltransferase inhibitors provide support for the specificity of the histochem

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01455.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—Synaptosomes were prepared from the cerebral cortex of the adult rat by a rapid technique, involving the use of centrifugation in a Ficoll‐sucrose discontinuous gradient. Adequate respiratory control ratios were obtained with glutamate and succinate plus rotenone. The addition of Na+to the incubation medium stimulated synaptosomal, State‐4 respiration, with a half‐maximal response at 15 mM Na+. The stimulation by Na+was inhibited by atractylate, oligomycin, ouabain or EDTA. A cooperative interaction between Na+and low concentrations of Mg2+was observed. A significant proportion (39 per cent) of the total Na‐K ATPase (EC 3.6.1.4) activity in the discontinuous gradient was localized in the synaptosomal fraction. In the absence of exogenous Mg2+, Na+induced a 64 per cent stimulation of the synaptosomal ATPase activity which was sensitive to ouabain. Such stimulation of ATP hydrolysis would account for the formation of increased amounts of ADP, with consequent recycling to ATP through adequately controlled oxidative phosphorylation. These observations demonstrate a significant role for transmembrane cationic gradients in the control of synaptosomal respiration and mitochondrial oxidative phosphorylation. The preparation exhibits moderate respiratory control and should prove useful in studies of integrated mitochondrial oxidative metabolism and neuronal membrane

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01456.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract—An actomyosin‐like protein (neurostenin) has been isolated from the synaptosomal fraction of bovine and rat brains. A similar protein could not be obtained from the mitochondrial, microsomal, myelin or supernatant fractions. The synaptosomal protein is a Mg2+‐Ca2+‐stimulated ATPase which exhibited the phenomenon of superprecipitation and viscosimetric sensitivity to ATP characteristic of actomyosins. It constituted 8–10 per cent of the total synaptosomal proteins. The protein could be dissociated into actin‐like (neurin) and myosin‐like (stenin) proteins by ultracentrifugation in sucrose gradients containing KI and ATP. The neurin, as well as muscle actin, stimulated the Mg2+‐ATPase activity of stenin and muscle myosin; the relative viscosities of the mixtures were increased and became sensitive to added ATP. The neurin contained 0.9 mol of 3‐methylhistidine per 50,000 g of protein. The presence of these proteins in the synaptosomes suggests the possibility that they participate in nerve‐ending functions, e.g. release of tr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1972.tb01457.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY