A rapid radwhemical assay for acetylcholine

Dunant, Yves; Hirt, Lieselotte

doi:10.1111/j.1471-4159.1976.tb01533.x

Cited by 16 publications

(5 citation statements)

References 6 publications

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“…The ACh level was measured by conventional frog rectus or leech dorsal muscle bioassays. Identical results were obtained with a radiochemical assay (Dunant and Hirt, 1976) and, in the most recent experiments, with the luminescence method of Israel and Lesbats (1981).…”

Section: Separation and Identification Of Metabolitessupporting

confidence: 64%

Incorporation of Acetate into Acetylcholine, Acetylcarnitine, and Amino Acids in the Torpedo Electric Organ

Corthay¹,

Dunant²,

Eder³

et al. 1985

Journal of Neurochemistry

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The metabolism of acetate was investigated in the nerve-electroplaque system of Torpedo marmorata. In intact fragments of electric organ, radiolabeled acetate was incorporated into acetylcholine (ACh), acetylcarnitine (ACar), and three amino acids: aspartate, glutamate, and glutamine. These compounds were identified by TLC, high-voltage electrophoresis, column chromatography, and enzymic tests. The system responsible for acetate transport and incorporation into ACh displayed a higher affinity but a lower Vmax than that involved in the synthesis of ACar and amino acids. Choline, when added to the medium, increased the rate of acetate incorporation into ACh but decreased (at concentrations greater than 10(-5) M) that into ACar and amino acids. Monofluoroacetate slightly depressed ACh and ACar synthesis from external acetate but inhibited much more the synthesis of amino acids. During repetitive nerve stimulation, the level of the newly synthetized [14C]ACh was found to oscillate together with that of endogenous ACh, but the level of neither [14C]ACar nor the 14C-labeled amino acids exhibited any significant change as a function of time. This means that there is probably no periodic transfer of acetyl groups between ACh and the investigated metabolites in the course of activity. Acetate metabolism was also tested in the electric lobe (which contains the cell bodies of the neurons innervating the electric organ) and in Torpedo synaptosomes (which are nerve terminals isolated from the same neurons). Radioactive pyruvate and glutamine were also assayed in some experiments for comparison with acetate. These observations are discussed in connection with ACh metabolism under resting and active conditions in tissues where acetate is the preferred precursor of the neurotransmitter.

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Section: Separation and Identification Of Metabolitessupporting

confidence: 64%

Incorporation of Acetate into Acetylcholine, Acetylcarnitine, and Amino Acids in the Torpedo Electric Organ

Corthay¹,

Dunant²,

Eder³

et al. 1985

Journal of Neurochemistry

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“…Nevertheless, we tested the effects of 4-AP on cholinesterase activity. This was measured in homogenates of electric organ by the method of Dunant & Hirt (1976), using ACh as substrate. It was found that 4-AP up to 10-4 M does not inhibit cholinesterase of this tissue to a measurable extent.…”

Section: Effects Of 4-ap On Nerve-electroplaque Transmission and Evokmentioning

confidence: 99%

Acetylcholine changes underlying transmission of a single nerve impulse in the presence of 4‐aminopyridine in Torpedo

Corthay¹,

Dunant²,

Loctin³

1982

The Journal of Physiology

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SUMMARY1. Transmission of a single nerve impulse has been investigated at the nerveelectroplaque junction of Torpedo marmorata in the presence of 4-aminopyridine (4-AP), a drug which powerfully potentiates evoked transmitter release.2. Three methodological approaches were used conjointly. These were (i) electrophysiological recording of the compound electroplaque potential (e.p.p.), (ii) radiochemical measurement of evoked acetylcholine (ACh) release and (iii) analysis of the content of ACh and ATP in the tissue at brief time intervals during the course of the e.p.p. and soon after. The last was achieved by using a stimulator coupled to a rapid tissue freezer.3. In the response to a single stimulus, 4-AP enhanced in a dose-dependent manner the size of the e.p.p., increasing the duration much more than the amplitude. At

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“…I . 1.27) following the procedure of Johnson (1960); for the determination of acetylcholinesterase (EC 3.1.1.7) and choline acetyltransferase (EC 2.3.1.6), the procedure adapted by Dunant and Hirt (1976) was used. Cytochrome c oxidase (EC 1.9.3.1), a mitochondrial marker, was measured according to Cooperstein and Lazarow (1951).…”

Section: Biuchemical Determinationsmentioning

confidence: 99%

Phosphate Ion Transport in Rabbit Brain Synaptosomes

Salamin¹,

Deshusses

Straub³

1981

Journal of Neurochemistry

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Synaptosomes (vesicles of nerve endings) isolated from rabbit brain were studied as a model system for the uptake of inorganic phosphate. The phosphate uptake showed a sodium-dependent, saturable component with a Kt of 0.29 mM. The sodium-dependent component was larger at pH 6 than at pH 7.4 or 8. Application of potassium salts, ouabain, monensin, nigericin or FCCP decreased the uptake. The results indicate that the sodium-sensitive phosphate influx is dependent on the Na+ gradient and on the membrane potential, which might act, preferentially, on the transport of the monovalent phosphate ion.

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A rapid radwhemical assay for acetylcholine

Cited by 16 publications

References 6 publications

Incorporation of Acetate into Acetylcholine, Acetylcarnitine, and Amino Acids in the Torpedo Electric Organ

Incorporation of Acetate into Acetylcholine, Acetylcarnitine, and Amino Acids in the Torpedo Electric Organ

Acetylcholine changes underlying transmission of a single nerve impulse in the presence of 4‐aminopyridine in Torpedo

Phosphate Ion Transport in Rabbit Brain Synaptosomes

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