Characterization of nucleoside transport activity in rabbit cortical synaptosomes

1995 ◽  
Vol 73 (12) ◽  
pp. 1733-1741 ◽  
Author(s):  
Kenneth W. James ◽  
James R. Hammond
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Mammalian Species ◽  
Nucleoside Transport ◽  
Rabbit Brain ◽  
Facilitated Diffusion ◽  
Nucleoside Transporter ◽  
Uridine Uptake ◽  
Diffusion Systems ◽  
Total Transport

Rabbit central nervous system (CNS) preparations have been used to study the central effects of adenosine, but little is known about the specific uptake mechanisms in rabbit brain involved in the regulation of extracellular adenosine concentrations. The present study assessed the kinetic and pharmacological characteristics of the uptake of [3H]uridine (a poorly metabolized substrate for adenosine transporters) by rabbit cortical synaptosomes, to define the transporter subtypes involved and to evaluate species variability in transporter characteristics. [3H]Uridine transport into rabbit cortical synaptosomes was mediated by two saturable, facilitated diffusion systems with characteristics compatible with the es and ei transporter subtypes identified in other mammalian species. About 65% of the total transport was mediated by the es system, and Km estimates of 320 and 94 μM were determined for [3H]uridine uptake by the es and ei transporter, respectively. These results differ significantly from the subtype ratio and kinetic characteristics reported for rat and guinea pig cortical synaptosomes, where most of the transport was mediated by an ei subtype. Dipyridamole, dilazep, nitrobenzylthioinosine, R75231, solufiazine, and mioflazine were relatively more effective as inhibitors of es-mediated uptake (compared with ei), while the substrates adenosine, cytidine, and guanosine did not distinguish between the es and ei transporters in rabbit cortical synaptosomes. These results highlight the significant species–tissue variability in nucleoside transporter characteristics and subtype expression, and emphasize the need to characterize the transporters in human CNS tissue to allow the rational development of CNS-active therapeutics based on inhibition of nucleoside transport.Key words: nitrobenzylthioinosine, [3H]uridine, nucleoside transport, central nervous system, adenosine.

Heterogeneity of high affinity nitrobenzylthioinosine binding sites in mammalian cortical membranes: multiple forms of central nervous system nucleoside transporters?

1984 ◽  
Vol 62 (8) ◽  
pp. 961-963 ◽  
Author(s):  
James R. Hammond ◽  
Alexander S. Clanachan
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Guinea Pig ◽  
Binding Sites ◽  
Specific Binding ◽  
Mammalian Species ◽  
Nucleoside Transport ◽  
Single Class ◽  
The Central Nervous System ◽  
Cortical Membranes

Specific binding of [3H]nitrobenzylthioinosine to cortical membranes from several mammalian species was investigated. Rat, mouse, guinea pig, and dog membranes contained an apparent single class of binding sites; there was, however, a marked species-dependent variation in their affinity for [3H]nitrobenzylthioinosine. Rabbit cortical membranes contained two classes of binding sites and the high and low affinity components were similar to those found in guinea pig and dog cortical membranes, respectively. The [3H]nkrobenzylthioinosine binding sites in rat and the low affinity sites in rabbit were atypical in that they exhibited a low affinity for dipyridamole. It is proposed that these latter sites may represent a form of the central nervous system nucleoside transport system which is less susceptible to inhibition by dipyridamole.

scholarly journals Spatial distribution and characterization of non-apical progenitors in the zebrafish embryo central nervous system

Open Biology ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 160312 ◽  
Author(s):  
Rebecca McIntosh ◽  
Joseph Norris ◽  
Jon D. Clarke ◽  
Paula Alexandre
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Mammalian Species ◽  
Small Population ◽  
Mammalian Brain ◽  
Molecular Characteristics ◽  
Apical Surface ◽  
Brain Expansion

Studies of non-apical progenitors (NAPs) have been largely limited to the developing mammalian cortex. They are postulated to generate the increase in neuron numbers that underlie mammalian brain expansion. Recently, NAPs have also been reported in the retina and central nervous system of non-mammalian species; in the latter, however, they remain poorly characterized. Here, we characterize NAP location along the zebrafish central nervous system during embryonic development, and determine their cellular and molecular characteristics and renewal capacity. We identified a small population of NAPs in the spinal cord, hindbrain and telencephalon of zebrafish embryos. Live-imaging analysis revealed at least two types of mitotic behaviour in the telencephalon: one NAP subtype retains the apical attachment during division, while another divides in a subapical position disconnected from the apical surface. All NAPs observed in spinal cord lost apical contact prior to mitoses. These NAPs express HuC and produce two neurons from a single division. Manipulation of Notch activity reveals that neurons and NAPs in the spinal cord use similar regulatory mechanisms. This work suggests that the majority of spinal NAPs in zebrafish share characteristics with basal progenitors in mammalian brains.

scholarly journals The effects of oestradiol on nucleoside transport in rat uterus

1971 ◽  
Vol 121 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Janet M. Oliver
Keyword(s):  
Cytosine Arabinoside ◽  
Concentration Gradient ◽  
Initial Rate ◽  
Nucleoside Transport ◽  
Facilitated Diffusion ◽  
Rat Uterus ◽  
Intracellular Space ◽  
Uridine Uptake

1. By using the non-metabolized cytidine analogue, cytosine arabinoside, it was possible to examine the mechanism of nucleoside transport in the immature rat uterus in the absence of intracellular utilization of the permeant. It was demonstrated that the uptake of cytosine arabinoside is not accumulative and that it can be competitively inhibited by the addition of a second nucleoside, uridine. Introduction of a concentration gradient of uridine from the medium towards the intracellular water promotes the counterflow of cytosine arabinoside out of the cells against its concentration gradient. These properties indicate that a facilitated-diffusion system is involved in nucleoside transport in the uterus. Further counterflow studies have shown that the transport system has a broad specificity for purine and pyrimidine nucleosides and that it is distinct from the processes that mediate the uptake of sugars, amino acids and purine and pyrimidine bases. 2. Oestradiol injection has no effect on the initial rate of cytosine arabinoside uptake in vitro. The increased amount of the analogue taken up per uterus is simply due to the expansion of the uterine volume that accompanies oestrogen action. 3. It is concluded that the striking increase in uridine uptake, observed in vivo in uteri from oestrogen-treated rats, does not result from an increase in the initial rate of nucleoside transport into the intracellular space of the tissue.

scholarly journals THE RAPID PRODUCTION OF ACUTE DISSEMINATED ENCEPHALOMYELITIS IN RHESUS MONKEYS BY INJECTION OF HETEROLOGOUS AND HOMOLOGOUS BRAIN TISSUE WITH ADJUVANTS

1947 ◽  
Vol 85 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Elvin A. Kabat ◽  
Abner Wolf ◽  
Ada E. Bezer
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Rhesus Monkeys ◽  
Demyelinating Disease ◽  
Acute Disseminated Encephalomyelitis ◽  
Rabbit Brain ◽  
Adult Rabbit ◽  
Rabbit Lung ◽  
The Central Nervous System ◽  
Experimental Findings

1. A picture resembling acute disseminated encephalomyelitis in the human being has been regularly and rapidly produced in rhesus monkeys by injection of emulsions of adult rabbit and monkey brain administered with adjuvants. 2. No lesions of the central nervous system resulted from injection of similar emulsions of fetal rabbit brain or adult rabbit lung. 3. A description of the gross and histological findings in the central nervous system is given and compared with features of human demyelinating disease. 4. The experimental findings are in accord with the hypothesis that antibody to the injected brain emulsion reacts with the tissues of the nervous system of the animal to produce the pathological changes.

scholarly journals Multiple sodium-dependent nucleoside transport systems in bovine renal brush-border membrane vesicles

1991 ◽  
Vol 274 (1) ◽  
pp. 27-33 ◽  
Author(s):  
T C Williams ◽  
S M Jarvis
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Nucleoside Transport ◽  
Transport Systems ◽  
Facilitated Diffusion ◽  
Nucleoside Transporter ◽  
Renal Brush Border Membrane ◽  
Renal Brush Border

Na(+)-dependent nucleoside transport was examined in bovine renal brush-border membrane vesicles. Two separate Na+/nucleoside cotransporters were shown to be present: (1) a system specific for purine nucleosides and uridine, designated as the N1 carrier, and (2) an Na(+)-dependent nucleoside transporter that accepts pyrimidine nucleosides, adenosine and analogues of adenosine, designated as the N2 system. Both systems exhibit a high affinity for nucleosides (apparent Km values approximately 10 microM), are insensitive to inhibition by facilitated-diffusion nucleoside transport inhibitors, are rheogenic and exhibit a high specificity for Na+. Na+ increases the affinity of the influx of guanosine and thymidine, nucleosides that serve as model permeants for the N1 and N2 nucleoside transporters respectively. The Na+/nucleoside coupling stoichiometry is consistent with 1:1 for both carriers.

scholarly journals OBSERVATIONS ON ATTEMPTS TO PRODUCE ACUTE DISSEMINATED ENCEPHALOMYELITIS IN MONKEYS

1933 ◽  
Vol 58 (1) ◽  
pp. 39-53 ◽  
Author(s):  
Thomas M. Rivers ◽  
D. H. Sprunt ◽  
G. P. Berry
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Acute Disseminated Encephalomyelitis ◽  
Vaccine Virus ◽  
Rabbit Brain ◽  
Exact Relation ◽  
Intramuscular Injections ◽  
Brain Extracts ◽  
The Central Nervous System ◽  
Combined Action

No evidence was found to support the idea that vaccine virus placed in the cisterna magna is capable of producing an acute disseminated encephalomyelitis with perivascular demyelination either in normal or in partially immune monkeys. A testicular extract (Reynals' factor) did not induce vaccine virus to cause an acute disseminated encephalomyelitis in monkeys. Repeated intramuscular injections of brain extracts and brain emulsions into eight monkeys were followed in two instances by an inflammatory reaction, accompanied by demyelination, in the central nervous system. The exact relation of the injections to the disease of the nervous system is not clear. The combined action of vaccine virus and an emulsion of fresh rabbit brain did not lead to the production of an acute disseminated encephalomyelitis in monkeys that had received repeated intramuscular injections of emulsions and alcohol-ether extracts of normal rabbit brains.

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