Potentials, electric evoked

In vivo, 5-HT4 agonists are clearly prokinetic [44,133] and display a wide range of therapeutic applications in gastrointestinal motility disorders. ether or not their therapeutic actions are entirely mediated by 5-HT4-RS is not clear. In isolated human stomach, renzapride has been shown to potentiate electrically-evoked contractions [84]. This effect was antagonized by mM concentrations of tropisetron, suggesting that 5-HT4-RS are involved [85]. 5-HT4-RS are also present in human small intestinal mucosa [86] where the non neuronal electrogenic secretory effect of 5-HT appears to be mediated by 5-HT4-RS. 

MacLeod N. and Reinhardt W. (1983). An electrophysiological study of the accessory olfactory bulb in rabbit — I. Analysis of electrical evoked potential fields. Neuroscience 10, 119-129. 

Gifford AN, Ashby CR. Electrically evoked acetylcholine release from hippocampal slices is inhibited by the cannabinoid receptor agonist, WIN 55212-2, and is potentiated by the cannabinoid antagonist, SR 141716A. J Pharmacol Exp Ther 1996 277 1431-1436. 

In electrophysiological studies aimed at elucidating the mechanism of action of kappa agonists, U-50488 has been shown to depress excitatory post-synaptic potentials in a rat locus coeruleus preparation, which indicates that it acts presynaptically to inhibit transmitter release [38]. Also, in spinal cord slice preparations from the 9-16-day-old rat, U-69593 (9) produced a naloxone-reversible depression of spontaneous and electrically evoked activity in dorsal horn neurones [39],... 

A second antagonist, AM 630 (24b), a novel aminoalkylindole, was found to attenuate the ability of some cannabinoids to inhibit electrically-evoked twitches of the mouse isolated vas deferens [114]. AM 630 was a more potent antagonist of d9-THC than of anandamide (Kd of 14.0 and 278.8 nM, respectively). It was suggested that the receptors for which AM 630 has the highest activity may not be CB, cannabinoid receptors. This is supported by the observation that AM 630 is actually a cannabinoid agonist in the myenteric plexus - muscle preparation [115]. Yamada et al. [116] showed that isothiocyanate derivatives of pravadoline can serve as potential electrophilic affinity ligands for CB],... 

There are useful tests to identify toxic effects on the peripheral nerves. Studies such as nerve conduction tests (NCSs) and electromyographic tests (EMGs) are used to identify the tingling or numbness of the hands or feet or associated muscle weakness. A set of neuropsychometric tests has also been developed to find behavioral effects of solvents in humans. These include but are not limited to (1) motor speed (2) hand steadiness (3) perceptual speed (4) reaction speed, eye-hand coordination, and manual dexterity (5) verbal and visual memory and learning and (6) cortical evoked potentials (electrical activity in the brain following sensory stimulation). ... 

Zheng J, Ren T, Parthasarathi A, NuttaU AL. 2001b. Quinine-induced alterations of electrically evoked otoacoustic emissions and cochlear potentials in guinea pigs. Hear Res 154 124-134. 

A common technique to study the enteric nerves is by measuring changes in motility caused by electrical field stimulation (EES). In this procedure, both sensory and motor nerves are activated in whole segments or motor nerve function in segments without mucosa and submucosa. EES cause cholinergic-mediated contraction and nitrergically mediated relaxation. Dmgs are used to study the effect and mechanism of inhibition or the potentiation of electrically evoked smooth muscle... 

The slice is electrically stimulated with an enamel-coated bipolar wire electrode causing action potentials that evoke DA release. In the slice preparation, the stimulation is applied directly at the neuron terminals. This is in contrast to an in vivo experiment, where the stimulation is performed at the cell body of the neuron and the DA release is monitored remotely at the presynaptic terminals. DA concentration in the extracellular fluid rises and quickly returns to baseline at the cessation of the stimulation [3]. Fast scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes is used to detect the resulting concentration changes in the extracellular fluid. This analytical technique provides a method for the determination of uptake kinetics in intact brain tissue. Thus, the secretion and subsequent clearance of DA in the tissue is observed in real time. 

FIG. 2 Measurements of intracellular potentials in sieve tubes of maize via severed aphid stylets. Stimulation by ice water (above) and electric shock (below) evoked action potentials which were propagated with a velocity of 3-5cms in a basipetal direction. (From Ref. 36.)... 

Evoked potential testing A procedure in which sensory nerve pathways are stimulated and the time lapse to electrical response in the corresponding area of the brain is measured. 

Quantal analysis defines the mechanism of release as exocytosis. Stimulation of the motor neuron causes a large depolarization of the motor end plate. In 1952, Fatt and Katz [11] observed that spontaneous potentials of approximately 1 mV occur at the motor endplate. Each individual potential change has a time course similar to the much larger evoked response of the muscle membrane that results from electrical stimulation of the motor nerve. These small spontaneous potentials were therefore called... 

Skrede, K. K. and Malthe-Sorenssen, D. Increased resting and evoked release of transmitter following repetitive electrical tetanization in hippocampus a biochemical correlate to long-lasting synaptic potentiation. Brain Res. 208 436—441,1981. 

The human eye is a more or less spherical organ located in the orbit, a cavity in the skull of the anterior head. The main task of the eye is the dioptric function, focusing the ambient light on the retina to evoke electric potentials which can be transmitted via the optic nerve to the brain to create visual impressions (Fig. 1). 

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