scholarly journals The early time course of potassium-stimulated calcium uptake in presynaptic nerve terminals isolated from rat brain.

1985 ◽  
Vol 361 (1) ◽  
pp. 251-268 ◽  
Author(s):  
D A Nachshen
Keyword(s):  
Rat Brain ◽  
Time Course ◽  
Calcium Uptake ◽  
Early Time ◽  
Nerve Terminals ◽  
Presynaptic Nerve Terminals

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.

Time-Course Effects of GA, GB, GD, GF and VX on Spinal Cord Cholinesterase and Acetylcholine Levels in Six Discrete Areas of the Rat Brain

2001 ◽  
Author(s):  
Bernard J. Benton ◽  
John H. McDonough ◽  
Thomas A. Koviak ◽  
Tsung-Ming A. Shih
Keyword(s):  
Spinal Cord ◽  
Rat Brain ◽  
Time Course
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