Comparative studies on mitochondria isolated from neuron-enriched and glia-enriched fractions of rabbit and beef brain
TL;DR: The difference in the buoyant density of mitochondria isolated from the neuron-enriched and glia-en enriched cell fractions was utilized in attempts to separate neuronal and glial mitochondria from the mixed mitochondria obtained from whole brain homogenates in shallow sucrose gradients.
Abstract: Fractions enriched in neuronal and glial cells were obtained from dispersions of whole beef brain and rabbit cerebral cortex by large-scale density gradient centrifugation procedures. The fractions were characterized by appropriate microscopic observation. Mitochondria were then isolated from these fractions by differential centrifugation of their homogenates. The two different types of mitochondria were characterized with respect to certain enzyme activities, respiratory rate, rate of protein synthesis, and their buoyant density in sucrose gradients. The mitochondria from the neuron-enriched fraction were distinguished by a higher rate of incorporation of amino acids into protein, higher cytochrome oxidase activity, and a higher buoyant density in sucrose density gradients. Mitochondria from the glia-enriched fraction showed relatively high monoamine oxidase and Na+- and K+-stimulated ATPase activities. The rates of oxidation of various substrates and the acceptor control ratios did not differ appreciably between the two types of mitochondria. The difference in the buoyant density of mitochondria isolated from the neuron-enriched and glia-enriched cell fractions was utilized in attempts to separate neuronal and glial mitochondria from the mixed mitochondria obtained from whole brain homogenates in shallow sucrose gradients. The appearance of two peaks of cytochrome oxidase, monoamine oxidase, and protein concentration in such gradients shows the potential feasibility of such an approach.
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TL;DR: Findings support the view that the high-affinity sites represent the ligand-binding sites of a specific Ca(2+) ;permease' or transport system in the membrane.
Abstract: A survey was made of the capacity of mitochondria isolated from a number of different tissues and species to accumulate Ca(2+) from the suspending medium during electron transport The species examined included the rat, mouse, rabbit, hamster, guinea pig, cow, chicken, turtle, blowfly, yeast and Neurospora crassa The tissues examined included vertebrate liver, kidney, brain, heart, spleen, thyroid and adrenal cortex, and the flight muscle of the blowfly The mitochondria from all vertebrate tissues examined showed: (a) stimulation of State 4 respiration by added Ca(2+) (Ca(2+)/~ activation ratio about 20), accompanied by accumulation of Ca(2+) and ejection of H(+), with a H(+)/Ca(2+) ratio about 10; (b) a requirement of phosphate for accumulation of large amounts of Ca(2+); (c) respiration-independent high-affinity binding sites for Ca(2+); (d) endogenous Ca(2+), which is largely released by uncoupling agents However, mitochondria from yeast and blowfly flight muscle are unable to accumulate Ca(2+) in a respiration-dependent process and possess no high-affinity Ca(2+)-binding sites These findings support the view that the high-affinity sites represent the ligand-binding sites of a specific Ca(2+) ;permease' or transport system in the membrane The relatively high affinity for Ca(2+), which equals or exceeds the affinity for ADP, and the generally uniform characteristics of Ca(2+) transport in all the vertebrate mitochondria tested strongly suggest that respiration-linked Ca(2+) accumulation plays a general and fundamental role in vertebrate cell physiology
329 citations
TL;DR: This chapter discusses the monoamine oxidases (MAO) and the MAO inhibitor drugs and it appears that MAO B is more sensitive to heat than MAO A and the thermostability of MAO preparations was dependent on the presence of phospholipid.
317 citations
TL;DR: Putative neuronal membrane markers, gangliosides and sodium, potassium-dependent ATPase, were enriched over 10-fold in these membranes in comparison to the homogenate, which suggests some contamination with glial cell plasma membrane.
301 citations
TL;DR: The results indicate that brain mitochondria are heterogeneous with respect to maximal activities of certain enzymes concerned with the citric acid cycle and glutamate and 4‐aminobutyrate metabolism as well as their ability to utilize various substrates.
Abstract: — A method has been developed where by three distinct populations of metabolically active, well coupled and relatively pure mitochondria from rat brain may be prepared. Two mitochondrial populations are derived from synaptozomes and the third consists of ‘free’ (i.e. non-synaptic) mitochondria. These mitochondrial populations have been characterized with respect to both enzyme content and ability to oxidize substrates. The results indicate that these mitochondrial populations are heterogeneous with respect to maximal activities of certain enzymes concerned with the citric acid cycle and glutamate and 4-aminobutyrate metabolism as well as their ability to utilize various substrates. The data reported here also confirm that brain mitochondria are very heterogeneous and suggest that synaptic mitochondria may contain at least two sub-populations. The relations between the heterogeneity of brain mitochondria and the metabolic compartmentation of the citric acid cycle and related metabolites such as glutamate, aspartate and 4-aminobutyrate are briefly discussed in the light of two proposed models of metabolic compartmentation in the mammalian brain.
257 citations
TL;DR: The author reviews modern information concerning the formation, flow and functions of the cerebrospinal fluid and gives particular attention to the lymphatic-like features of the third circulation.
Abstract: ✓ The author reviews modern information concerning the formation, flow, and functions of the cerebrospinal fluid. Particular attention is given to the lymphatic-like features of the third circulation and to its importance as an internal milieu for nervous tissue.
204 citations
References
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Book•
01 Jan 1963
TL;DR: Methods of enzymatic analysis, Methods of enzymes analysis, the authors, Methods of enzyme analysis, enzymatics, methods of enzymes, and methods of analysis, method of enzymes.
Abstract: Methods of enzymatic analysis , Methods of enzymatic analysis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
18,100 citations
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TL;DR: De Robertis and Carrea as mentioned in this paper published a book on the biology of neuroglia called "Biology of Neuroglia Edited By E D P deRobertis and R Carrea (Progress in Brain Research, Vol 15) Pp xi + 297 (Amsterdam, London and New York: Elsevier Publishing Company, 1965) 95s
Abstract: Biology of Neuroglia Edited By E D P de Robertis and R Carrea (Progress in Brain Research, Vol 15) Pp xi + 297 (Amsterdam, London and New York: Elsevier Publishing Company, 1965) 95s
9 citations