Search results for "Inhibitory postsynaptic potential"

Vasodilator Effects of Liriodenine and Norushinsunine, Two Aporphine Alkaloids Isolated from <i>Annona cherimolia,</i>in Rat Aorta

1995

The effect of two aporphines, liriodenine and norushinsunine, isolated from Annona cherimolia, were studied in the rat aorta in order to examine their mechanism of action. Both alkaloids (10–7–10–4 mol/l) showed relaxant effects on the contractions elicited by 10–6 mol/l noradrenaline (NA) or 80 mmol/l KC1, but, while liriodenine showed a nonspecific relaxant action on both spasmogens, norushinsunine was more potent on KC1-induced contraction. In Ca2+-free medium, both alkaloids (0.1 mmol/l) inhibited the responses elicited by NA, but not those elicited by caffeine. This inhibitory action occurred when the alkaloids were present during the release of the Ca2+ internal stores or during the r…

Screening of cyanobacteria extracts for inhibitory activity against the cysteine protease rhodesain of Trypanosoma brucei

2016

Die Reversibilität der Wirkung von Digitoxin, Strophanthidin und Strophanthidin-3-bromazetat am Papillarmuskel und einer mikrosomalen Na+-K+-aktivier…

1969

The reversibility of the inhibitory action of strophanthidin, strophanthidin-3-bromoacetate, and digitoxin on the Na+-K+-ATPase activity (microsomal fraction, guinea-pig brain) was compared with the rate of decline of their positive inotropic effects (papillary muscle, guinea-pig heart) after exposure to drug-free solution. The actions of strophanthidin and digitoxin were easily reduced on both systems. Strophanthidin-3-bromoacetate, however, was found to have an irreversible blocking effect on the transport ATPase, whereas its inotropic action could be rapidly abolished.

Tonic inhibitory action by nitric oxide on spontaneous mechanical activity in rat proximal colon: involvement of cyclic GMP and apamin-sensitive K+ c…

1999

The cellular mechanisms by which endogenous nitric oxide (NO) modulates spontaneous motility were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. Apamin (1–100 nM) produced a concentration-dependent increase in the amplitude of the spontaneous pressure waves. The maximal contractile effect was of the same degree as that produced by Nω-nitro-L-arginine methyl ester (L-NAME) (100 μM) and the joint application of apamin plus L-NAME had no additive effects. Apamin (0.1 μM) reduced the inhibitory effects (i.e. reduction in the amplitude of the pressure waves) induced by sodium nitroprusside (SNP) (1 nM–10 μM) or 8-Br-cyclic G…

The variation of acetylcholine release from myenteric neurones with stimulation frequency and train length. Role of presynaptic muscarine receptors.

1983

1. The effects of scopolamine on the release of 3H-acetylcholine (ACh) from the guinea-pig myenteric plexus were studied at different stimulation frequencies (0.03–10 Hz) and train lengths (1–180 pulses). Release of 3H-ACh was measured in the absence of cholinesterase inhibitors as the outflow of tritium from myenteric plexus-longitudinal muscle preparations preloaded with 3H-choline. 2. In control experiments the volley output of 3H-ACh declined with increasing train length and increasing stimulation frequency. Stimulation by one pulse produced the highest volley output. 3. Scopolamine facilitated the evoked output of 3H-ACh via blockade of presynaptic muscarine receptors. A significant in…

The action of iontophoretically applied acetylcholine and dopamine on single claustrum neurones in the cat.

1981

Abstract The effects of iontophoretically applied acetyl-choline (ACh) and dopamine (DA) on spontaneously active claustral neurones, in chloralose-anaesthetised cats, have been investigated. Acetylcholine had both facilitatory and inhibitory effects in almost the same proportions. The action of DA was prevalently inhibitory. Two types of inhibitory response to ACh and DA are described: short-lasting inhibition and long-lasting inhibition. The excitatory response always outlasted the period of drug application.

Time course of excitatory and inhibitory states of bulbar respiratory modulated neurons.

1980

In respiratory modulated neurons of rabbits, vagally mediated inhibition is not bound to resting membrane potential oscillations. Latency of spinally evoked antidromical spike invasion, however, is shorter and threshold voltage is lower during the shift of membrane potential towards depolarization accompanying burst discharge.

Die Hemmbarkeit der inhibitorischen Adrenalinbzw. Noradrenalinwirkung durch Adrenolytika

1958

Dibenamine, dihydroergotamine, regitin and priscol were found to antagonize specifically the inhibitory action of adrenaline and noradrenaline on the electrically stimulated isolated ileum of the guinea-pig. The antagonistic action of dibenamine was irreversible.

Der Antagonismus verschiedener Sympatholytica gegen�ber dem inhibitorischen Adrenalin- oder Noradrenalineffekt am elektrisch gereizten Meerschweinche…

1958

Adrenaline and noradrenaline were found to depress the contractions of the electrically stimulated isolated ileum of the guinea-pig; this action was related to the dose. In these experiments smaller amounts of adrenaline were required than those necessary for the depression of the spontaneous movements of the isolated rabbit duodenum.

Effect of acetylcholine and dopamine iontophoretically applied on the sensory responsive caudate unit

1986

A putative integrative function of the striatum was evaluated through the study of the electrical activity of sensory responsive caudate neurones. Both nervous (radial nerve) and auditory stimulations were delivered in order to characterize populations of neurones affected by peripheral stimuli; the units were previously activated by iontophoretic glutamate. On these units the iontophoretic ejection of ACh and DA was tested. Experimental results demonstrated a prevalent excitatory effect of ACh, while DA appeared to exert a drastic decrease on firing rate. A comparison between peripheral stimuli and chemical substances was made. The result of such study showed a most important action of the…