The pharmacology of the amphibian spinal cord

Kudo, Yoshihisa

doi:10.1016/0301-0082(78)90007-2

Cited by 64 publications

(19 citation statements)

References 259 publications

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“…Dorsal root stimulation in frog spinal cord preparations generates a depolarization of several millivolts amplitude and several seconds' duration recorded in the corresponding ventral root (Barron & Matthews, 1938). Such ventral root potentials are believed to contain only a small monosynaptic component (Fadiga & Brookhart, 1962; see also review by Kudo, 1978). The chart recorder (Smith's Industries Servoscribe) used in the present study had a minimum time to full scale deflection of 150 ms. Consequently the peak amplitude of these electrically evoked potentials, which occurred within the initial 50 ms, was not registered.…”

Section: Measurement Of Depressantpotencymentioning

confidence: 94%

The EFFECTS OF a SERIES OF Ω‐PHOSPHONIC Α‐CARBOXYLIC AMINO ACIDS ON ELECTRICALLY EVOKED AND EXCITANT AMINO ACID‐INDUCED RESPONSES IN ISOLATED SPINAL CORD PREPARATIONS

Evans¹,

Francis²,

Jones³

et al. 1982

British J Pharmacology

463

181

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1 The depressant actions on evoked electrical activity and the excitant amino acid antagonist properties of a range of w-phosphonic x-carboxylic amino acids have been investigated in the isolated spinal cord preparations of the frog or immature rat. 2 When tested on dorsal root-evoked ventral root potentials, members of the homologous series from 2-amino-5-phosphonovaleric acid to 2-amino-8-phosphonooctanoic acid showed depressant actions which correlated with the ability of the substances to antagonize selectively motoneuronal depolarizations induced by N-methyl-D-aspartate. of this substance had a relatively weak and non-selective antagonist action on depolarizations induced by N-methyl-D-aspartate, quisqualate and kainate and a similarly weak depressant effect when tested on evoked electrical activity. The (+)-form was more potent than the (-)-form in depressing electrically evoked activity but did not antagonize responses to amino acid excitants. At concentrations higher than those required to depress electrically evoked activity, the (+)-form produced depolarization. This action was blocked by 2-amino-5-phosphonovalerate.

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Section: Measurement Of Depressantpotencymentioning

confidence: 94%

The EFFECTS OF a SERIES OF Ω‐PHOSPHONIC Α‐CARBOXYLIC AMINO ACIDS ON ELECTRICALLY EVOKED AND EXCITANT AMINO ACID‐INDUCED RESPONSES IN ISOLATED SPINAL CORD PREPARATIONS

Evans¹,

Francis²,

Jones³

et al. 1982

British J Pharmacology

463

181

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“…The dura was reflected and spinal roots 2-11 (nomenclature of Gaupp as described by Kudo, 1978) were sectioned at their exit points from the vertebral column. The spinal cord was transected just rostral to the anterior intumescentia, removed and either hemisected with a razor blade or cannulated and perfused through the ventral spinal artery using a fine glass pipette as described by Matsura et al (1969).…”

Section: Methodsmentioning

confidence: 99%

The actions of serotonin on frog primary afferent terminals and cell bodies

Holz

Anderson

1984

Comparative Biochemistry and Physiology Part C: Comparative Pha

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Abstract1. The actions of serotonin (5-HT) were studied in the isolated frog spinal cord and dorsal root ganglion preparations. 2.In the spinal cord, 5-HT increased the spontaneous activity recorded from dorsal roots, facilitated evoked spinal reflexes and produced fast and slow primary afferent depolarization (PAD). 3.A direct action of 5-HT on primary afferent terminals is likely since 5-HT induced PAD remained in the presence of 1 µM tetrodotoxin and 2 mM Mn 2+ . 4.The direct action of 5-HT on primary afferent terminals was blocked by methysergide and attenuated by concentrations of Mn 2+ in excess of that required to block transmitter release. 5.Cell bodies of the dorsal root ganglion were also depolarized by 5-HT. A slow hyperpolarization occasionally followed the initial depolarization. The depolarizing action of 5-HT in the dorsal root ganglion was also attenuated by treatment with Mn 2+ .6. It is concluded that 5-HT acts directly on frog primary afferents and that this influence may involve a calcium sensitive process. The dorsal root ganglion response to 5-HT appears to be a suitable model of the afferent terminal response.

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“…The present study was therefore undertaken to investigate the effect of PTX on the central nervous system using the isolated spinal cord of the frog (Kudo, 1978 (Kudo, Abe, Goto & Fukuda, 1975 The sucrose-gap method applied in the present study has been described by Kudo et al (1975 Influence of tetrodotoxin and Na-deficient solution After treatment of the spinal cord with TTX (10-7 M), the depolarizations of ventral and dorsal roots evoked by in four experiments were reduced to an insignificant degree by 9.3 + 4.7% and 8.8 + 4.3%, respectively. Concentration (M) Figure 2 The dose-response relationships for palytoxin (PTX) on the resting root potentials: (0) In NaCl-deficient solution, the depolarizations evoked by PTX (10-8 M) were significantly reduced as were the attenuation of evoked root potentials (Table 1).…”

Section: Introductionmentioning

confidence: 99%

THE POTENT DEPOLARIZING ACTION OF PALYTOXIN ISOLATED FROM Palythoa Tubercurosa ON THE ISOLATED SPINAL CORD OF THE FROG

Kudo

Shibata

1980

British J Pharmacology

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The effects of palytoxin (PTX) isolated from Palythoa tubercurosa were tested on the isolated intra‐arterially perfused spinal cord of the frog. The resting and evoked potentials were recorded by means of a sucrose‐gap technique. PTX caused a marked depolarization of both ventral and dorsal roots. The minimum effective concentration was extremely low, approximately 10−11 m. During the depolarization the evoked ventral and dorsal root potentials were markedly reduced in amplitude. The ventral root reflex was first augmented and then decreased. The depolarization caused by PTX was markedly reduced when the preparation was perfused with NaCl ‐deficient medium. However, tetrodotoxin (10−7 m) only slightly inhibited the depolarization. In a high Ca2+ medium (3.6 mm), the time required to reach the maximum depolarization evoked by PTX was significantly prolonged. In contrast, in a low Ca2+ medium (0.9 mm), PTX caused a marked depolarization soon after application. In a Ca2+‐free, Mg2+ (9.0 mm) medium, PTX caused rhythmic oscillatory potentials in both ventral and dorsal roots. The potency of N‐acetyl PTX was one hundredth that of the parent compound. It is suggested that PTX may interfere with the stabilizing action of Ca2+ on the neuronal membrane, consequently facilitating Na+ permeability. The primary amine in the PTX molecule may be important for its pharmacological action.

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The pharmacology of the amphibian spinal cord

Cited by 64 publications

References 259 publications

The EFFECTS OF a SERIES OF Ω‐PHOSPHONIC Α‐CARBOXYLIC AMINO ACIDS ON ELECTRICALLY EVOKED AND EXCITANT AMINO ACID‐INDUCED RESPONSES IN ISOLATED SPINAL CORD PREPARATIONS

The EFFECTS OF a SERIES OF Ω‐PHOSPHONIC Α‐CARBOXYLIC AMINO ACIDS ON ELECTRICALLY EVOKED AND EXCITANT AMINO ACID‐INDUCED RESPONSES IN ISOLATED SPINAL CORD PREPARATIONS

The actions of serotonin on frog primary afferent terminals and cell bodies

THE POTENT DEPOLARIZING ACTION OF PALYTOXIN ISOLATED FROM Palythoa Tubercurosa ON THE ISOLATED SPINAL CORD OF THE FROG

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