Search results for "action potential"

Metabolic aspects of the rhythmogenesis inAplysia pacemaker neurons

1973

Completely isolatedAplysia pacemaker neurons were used to investigate mechanisms of endogenous electrical rhythmicity. This preparation allows the study of pure pacemaker activity free from synaptic, ephaptic and/or humoral influences from the surrounding cells. The effect of some substances quite different in their mode of biochemical action were tested: sodium iodoacetate, phloridzin, dinitrophenol, heavy water, and ouabain. Each of these substances suppressed the spontaneous spike activity without any marked depolarizing or hyperpolarizing effect. Spontaneous spike activity of the neurons silenced after addition of one of these substances reappeared after addition of glucose. The restori…

Der Einfluss von Acetylcholin auf den Calciumumsatz ruhender und kontrahierender Vorhofmuskulaturin vitro

1964

Acetylcholine 5 × 10−8 g/ml reduces the Ca45 uptake of the beating left atria of guinea-pig; the tissue calcium is not altered. In resting atria, acetylcholine 5 × 10−7 g/ml has no influence upon the calcium content and Ca45 uptake. It is concluded that acetylcholine acts by shortening the action potential duration and thereby reduces the release of cellular calcium per excitation.

Response of human ventricular heart muscle to histamine

1981

Temperature dependence of the toxic effects of phenytoin on peripheral neuromuscular function of the rat tail.

1990

We studied the acute effects of a single dose of phenytoin (250 mg/kg) on peripheral neuromuscular function. The evoked muscle action potentials of the dorsal segmental muscles in the rat tail, and the conduction velocity of the dorsal nerve trunk which innervates them, were measured before and after the intraperitoneal injection of phenytoin. The experiments were performed at different temperatures, 27 (physiological tail temperature), 36 and 37 degrees C (physiological central temperature) in different groups of animals. The amplitudes of the evoked muscle action potentials in the treated groups showed no significant modifications at 27 degrees C, at 36 degrees C a small nonsignificant de…

The spiked harmonic oscillatorV(r)=r 2+λr −4 as a challenge to perturbation theory

1991

The standard weak- and strong-coupling perturbation series are interpreted as extreme special cases of expansions obtainable within the framework of Rayleigh-Schroedinger perturbation theory with non-diagonal propagators and unspecified zero-order energies. The formalism of the latter type is then tested by our strongly singular example. It proves suitable for applications in the domain of virtually arbitrary couplings. A few related technicalities and especially the quadruple problem of convergence are also discussed.

Small-signal analysis of the encoder mechanism in the lobster stretch receptor and the frog and cat muscle spindle.

1975

Ausgehend von der Leitwert-Potential-Beziehung als Bedingung fur die Impulsauslosung an erregbaren Membranen (Chaplain, 1974) wird eine Kleinsignal-Analyse des Kodierungsvorganges in Mechanorezeptoren beschrieben. Hierbei wird die Theorie der Systeme mit zeitvariablen Parametern angewendet. Das beschriebene mathematische Modell erlaubt quantitative Aussagen fur den Frequenzgang unabhangig davon ob die Momentafrequenz oder die Impulsdichte als Ausgangssignal betrachtet wird. Die Approximation experimenteller Daten gelingt sowohl fur die Ansteuerung des Kodierers bei intrazellularer Stromstimulierung im Fall des Dehnungsrezeptors wie auch durch Leitwertanderungen als Folge des mechano-elektri…

Rotational excitation of mono- and doubly-deuterated water by hydrogen molecules

2011

Rate coefficients for rotational transitions in HDO and D2O induced by H2 collisions below 300 K are presented. Calculations have been performed at the close-coupling and coupledstates levels with the deuterated variants of the H2O–H2 interaction potential of Valiron et al. The HDO–H2 and D2O–H2 rate coefficients are compared to the corresponding rate coefficients for HDO–He and H2O–H2, respectively. Significant differences are observed. In particular the new HDO rate coefficients are found to be significantly larger (by up to three orders of magnitude) than the corresponding HDO–He rate coefficients. The impact of the new HDO rate coefficients is examined with the help of non-LTE radiative…

Calculated Line Broadening Coefficients in the nu2 Band of CH3D Perturbed by Helium

2003

International audience; Line broadening coefficients have been calculated, at room temperature, for lines in the P and R branches of the nu2 band of monodeuterated methane. A properly symmetrized semiclassical model with parabolic relative trajectories has been used. Two interaction potential models have been considered. The first is a Lennard-Jones type atom-atom potential, while the second one was derived from ab initio calculations. The calculated line widths were compared to the available experimental data and a satisfactory agreement was found, although the model contains no other adjustable parameters than the four atomic Lennard-Jones ones. Nonetheless, failures of calculations have …

Comparison of complex fractionated atrial electrograms at cellular scale using numerical and experimental models.

2010

This study investigates the existence of the pseudo complex fractionated atrial electrogram (CFAE) at cellular level. Our assumptions are based on the fact that CFAEs are linked to the generation of the spiral waves. These are created using a numerical model and an experimental model of in vitro culture of neonatal rats cardiac cells. Pseudo bipolar electrograms resulting from these two models are compared qualitatively and some patterns could be identified as CFAE signature.

TRESK channel contributes to depolarization-induced shunting inhibition and modulates epileptic seizures.

2020

Glutamatergic and GABAergic synaptic transmission controls excitation and inhibition of postsynaptic neurons, whereas activity of ion channels modulates neuronal intrinsic excitability. However, it is unclear how excessive neuronal excitation affects intrinsic inhibition to regain homeostatic stability under physiological or pathophysiological conditions. Here, we report that a seizure-like sustained depolarization can induce short-term inhibition of hippocampal CA3 neurons via a mechanism of membrane shunting. This depolarization-induced shunting inhibition (DShI) mediates a non-synaptic, but neuronal intrinsic, short-term plasticity that is able to suppress action potential generation and…