Different action of atropine and some analogues on the end-plate potentials and induced acetylcholine potentials

Zusammenfassung Mittels intrazellulärer Mikroelektroden wurde der Einfluss von 7 Tropinestern auf Amplitude und Umkehrpunkt (E _r ) der Endplattenpotentiale am M. sartorius des Frosches untersucht. Alle Substanzen erniedrigen die Amplitude und verändern die Form der Endplattenpotentiale, während 3 von ihnen den Umkehrpunkt (E _r ) in der Richtung zum Na-Gleichgewicht verschieben.     

Reaching-related potentials in caudate nucleus and cerebellum of rats

Summary Electrical correlates of the lateralized reaching reaction were studied in rats with implanted electrodes. Averaged event-related potentials (ERPs) in the cerebellar dentate nucleus consisted of a negative wave coinciding with reach onset and followed 70 msec later by a positive deflection. The most prominent component of the more variable caudate ERPs was a negative wave culminating 60–120 msec after reach onset. The positive and negative ERP deflections corresponded to inhibitory and excitatory reactions respectively, at the single neuron level.     

Interneuronal barrages and ripple superposed on inhibitory postsynaptic potentials

Résumé L'activité électrique des neurones du noyau thalamique ventro-latéral est étudiée ici chez des chats anesthésiés au nembutal et immobilisés avec du flaxedil au moyen d'un enregistrement intracellulaire. Nous avons observé que l'enregistrement de certains neurones montre que le potentiel nommé inhibiteur postsynaptique (IPSP) est accompagné de la décharge en barrage d'un autre neurone probablement semblable à la cellule deRenshaw.

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We thank Mr.G. Bilanow for invaluable technical help.     

Electroencephalogram potentials evoked by hemi-retinal stimulation

Zusammenfassung Als Reaktion auf Reizung der lateralen Gesichtsfeldhälfte wurden evozierte Potentiale der Hirnrinde des Menschen registriert. Reizung der einen Gesichtshälfte erzeugte frühzeitig ein Maximum der Potentiale der gegenseitigen Hemisphäre sowie Phasenumkehr der Potentiale der gleichseitigen Hemisphäre.     

Transmembrane potentials of the ductus arteriosus

Zusammenfassung Membran-Potentiale vom Ductus arteriosus der Ziege wurden im ruhenden Zustand aufgezeichnet. Die Zellen depolarisieren, sobald sie mit einer Kontraktion auslösenden Konzentration Sauerstoff in Berührung kommen.     

4-Aminopyridine and fiber potentials in rat and human hippocampal slices

Cellular and Molecular Life Sciences - Compound fiber action potentials of stratum radiatum afferents in slices from human and rat hippocampus are shown to be prolonged by 4-aminopyridine (4-AP)....     

Effect of drugs on excitatory and inhibitory potentials inHelix aspersa

Résumé Des produits chimiques furent injectés à l'escargotHelix aspersa. Leur effet fut enregistré en potentiels postsynaptiques. L'hemicholinium réduit l'amplitude d'un potentiel postsynaptique d'excitation cholinergique. L'-Methyl-5-HTP et lep-chlorophenylalanine ou résperpine font décroître l'amplitude d'un potentiel postsynaptique d'exication 5-HT, le 6-Hydroxydopamine diminue celle d'un potentiel postsynaptique d'inhibition dopamine tandis que le DOPA l'augmente.     

Sodium and calcium action potentials in human anterior pituitary cells

Summary Human anterior pituitary cells derived from a somatotropin-secreting adenoma were capable of generating action potentials with Ca²⁺ and tetrodotoxin-sensitive Na⁺ components. A major fraction of the action current was carried by Na ions.We wish to thank Dr O. Sand for correcting the English and Miss Michiko Takano for technical assistance. We also acknowledge the collaboration of Dr S. Miyazaki in the electron microscope.     

Periodic variations in motor endplate potentials]

The amplitudes of motor end-plate potentials in the Frog have been measured during repetitive stimulations of the motor nerve at frequencies between 0,5 and 30 Hz. A serial analysis showed that cyclic variations of these amplitudes were superimposed on the random fluctuation of epp due to the quantal nature of transmitter release. The period of these cyclic variations varied between 3 and 10 stimulations. This period was not significantly related to the frequency of the stimulation. The frequency spectrum analysis of the epp amplitudes showed similar values for the period of the cyclic variation of epp. The same kind of analysis applied to a binomial series of random numbers did not significantly present periodic fluctuations. The same analysis was applied to mean amplitudes of groups of 5 to 120 successive epps at the same end-plate. Periodic fluctuations were identified with periods of about 10 to 180 sec. It is suggested that periodic failures of nerve spike propagation in nerve terminals at sites of low safety factor, as at branchings, are responsible for the observed cyclic variation of epp.     

Spontaneous miniature potentials in primary afferent fibres

Summary Intracellular recording from primary afferent fibres of the isolated frog spinal cord revealed the existence of spontaneous synaptic activity, related probably to the firing of presynaptic inhibitory fibres.