scholarly journals Effect of NH4+ on synaptosomal membrane potential in the rat brain.

1988 ◽  
Vol 92 (6) ◽  
pp. 359-364 ◽  
Author(s):  
Reiko FUKUNAGA ◽  
Mitsuhiro SIMODA ◽  
Masayo OZASA ◽  
Chiyoko INAGAKI
Keyword(s):  
Membrane Potential ◽  
Rat Brain ◽  
Synaptosomal Membrane

scholarly journals Effect of ethanol on synaptosomal membrane potential in the rat brain.

1989 ◽  
Vol 94 (2) ◽  
pp. 119-122
Author(s):  
Wasako ODA-KURIO ◽  
Reiko FUKUNAGA ◽  
Chiyoko INAGAKI
Keyword(s):  
Membrane Potential ◽  
Rat Brain ◽  
Synaptosomal Membrane

Evidence of glutathione transporter in rat brain synaptosomal membrane vesicles

1999 ◽  
Vol 34 (6) ◽  
pp. 509-516 ◽  
Author(s):  
Teresa Iantomasi ◽  
Fabio Favilli ◽  
Maria T Vincenzini
Keyword(s):  
Rat Brain ◽  
Membrane Vesicles ◽  
Synaptosomal Membrane

Effect of Bilirubin on the Membrane Potential of Rat Brain Synaptosomes

2006 ◽  
Vol 47 (2) ◽  
pp. 363-369 ◽  
Author(s):  
F. Mayor ◽  
J. Díez-Guerra ◽  
F. Valdivieso ◽  
F. Mayor
Keyword(s):  
Membrane Potential ◽  
Rat Brain ◽  
Rat Brain Synaptosomes ◽  
Brain Synaptosomes

scholarly journals The regulation of cytosolic pH in isolated presynaptic nerve terminals from rat brain.

1988 ◽  
Vol 91 (2) ◽  
pp. 289-303 ◽  
Author(s):  
D A Nachshen ◽  
P Drapeau
Keyword(s):  
Rat Brain ◽  
Parent Compound ◽  
Mammalian Brain ◽  
Fluorescence Signal ◽  
Nerve Terminals ◽  
Free Medium ◽  
Cytosolic Ph ◽  
Methyl Ester Derivative ◽  
Synaptosomal Membrane ◽  
Presynaptic Nerve Terminals

Cytosolic pH (pHi) was measured in presynaptic nerve terminals isolated from rat brain (synaptosomes) using a fluorescent pH indicator, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). The synaptosomes were loaded with BCECF by incubation with the membrane-permanent acetoxy-methyl ester derivative of BCECF, which is hydrolyzed by intracellular esterases to the parent compound. pHi was estimated by calibrating the fluorescence signal after permeabilizing the synaptosomal membrane by two different methods. Synaptosomes loaded with 15-90 microM BCECF were estimated to have a pHi of 6.94 +/- 0.02 (mean +/- standard error; n = 54) if the fluorescence signal was calibrated after permeabilizing with digitonin; a similar value was obtained using synaptosomes loaded with 10 times less BCECF (6.9 +/- 0.1; n = 5). When the fluorescence signal was calibrated by permeabilizing the synaptosomal membrane to H+ with gramicidin and nigericin, pHi was estimated to be 7.19 +/- 0.03 (n = 12). With the latter method, pHi = 6.95 +/- 0.09 (n = 14) when the synaptosomes were loaded with 10 times less BCECF. Thus, pHi in synaptosomes was approximately 7.0 and could be more precisely monitored using the digitonin calibration method at higher BCECF concentrations. When synaptosomes were incubated in medium containing 20 mM NH4Cl and then diluted into NH4Cl-free medium, pHi immediately acidified to a level of approximately 6.6. After the acidification, pHi recovered over a period of a few minutes. The buffering capacity of the synaptosomes was estimated to be approximately 50 mM/pH unit. Recovery was substantially slowed by incubation in an Na-free medium, by the addition of amiloride (KI = 3 microM), and by abolition of the Nao/Nai gradient. pHi and its recovery after acidification were not affected by incubation in an HCO3-containing medium; disulfonic stilbene anion transport inhibitors (SITS and DIDS, 1 mM) and replacement of Cl with methylsulfonate did not affect the rate of recovery of pHi. It appears that an Na+/H+ antiporter is the primary regulator of pHi in mammalian brain nerve terminals.

Buffer systems variably affect the interaction of norepinephrine with brain Na+–K+ ATPase

1988 ◽  
Vol 66 (8) ◽  
pp. 1035-1040
Author(s):  
S. J. Mihic ◽  
P. H. Wu ◽  
H. Kalant
Keyword(s):  
Atpase Activity ◽  
Kinetic Analysis ◽  
Rat Brain ◽  
Reaction Conditions ◽  
Synaptosomal Membrane ◽  
High Affinity

The reported effects of norepinephrine (NE) on brain Na+–K+ ATPase are quite variable. Different investigators have reported activation, inhibition, or no effect. An investigation of the importance of reaction conditions on brain Na+–K+ ATPase activity was undertaken to resolve some of these discrepancies. Using porcine cerebral cortical Na+–K+ ATPase and rat brain synaptosomal membrane preparations, it was observed that NE strongly inhibited brain Na+–K+ ATPase in Tris–HCl buffer. This inhibition of the enzyme was reversed by the addition of EDTA. In contrast, NE did not significantly inhibit Na+–K+ ATPase in imidazole–glycylglycine and Krebs–Ringer–phosphate buffers. This buffer dependence of NE inhibition of the enzyme was consistently demonstrated with three different established methods for phosphate measurement. Kinetic analysis indicated that NE, in Tris–HCl buffer, inhibited the enzyme noncompetitively at high affinity, and competitively at low affinity, ATP substrate sites.

Effect of maitotoxin on cytosolic Ca2+ levels and membrane potential in purified rat brain synaptosomes

1990 ◽  
Vol 1026 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Maurizio Taglialatela ◽  
Lorella M.T. Canzoniero ◽  
Alessandro Fatatis ◽  
Gianfranco Di Renzo ◽  
Takeshi Yasumoto ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Rat Brain ◽  
Rat Brain Synaptosomes ◽  
Brain Synaptosomes
Sign in / Sign up

Export Citation Format

Share Document