Search results for " potential"
showing 10 items of 2713 documents
Failure of opioids to affect excitation and contraction in isolated ventricular heart muscle
1989
The opioid agonists morphine (selective for mu-receptors) and ethylketocyclazocine (selective for kappa-receptors), at concentrations evoking strong effects in neuronal structures, did not significantly affect the configuration of the intracellularly recorded action potential and the force of contraction in ventricular heart muscle isolated from guinea pigs, rabbits and man. These results suggest that any changes of heart functions in vivo in response to opioid-like drugs are probably not mediated postsynaptically at the myocardial cell membrane but rather presynaptically, influencing the release of noradrenaline and/or acetylcholine from the nerve terminals.
Changes in motor unit characteristics after eccentric elbow flexor exercise
2010
Morphological evidence suggests that fast-twitch fibers are prone to disruption of their membrane structures by eccentric exercise. However, it is unclear how this is reflected in the discharge rate and action potential propagation of individual motor units, especially at high contraction levels. High-density surface electromyograms were recorded from biceps brachii muscle and decomposed to individual motor unit action potentials at isometric contraction levels between 10% and 75% of maximal voluntary contraction (MVC) before intermittent maximal elbow flexor eccentric exercise, and two hours (2H), two days (2D) and four days (4D) post-exercise. Maximal voluntary force decreased by 21.3±5.6…
Changes in motor unit characteristics after eccentric elbow flexor exercise
2010
Morphological evidence suggests that fast-twitch fibers are prone to disruption of their membrane structures by eccentric exercise. However, it is unclear how this is reflected in the discharge rate and action potential propagation of individual motor units, especially at high contraction levels. High-density surface electromyograms were recorded from biceps brachii muscle and decomposed to individual motor unit action potentials at isometric contraction levels between 10% and 75% of maximal voluntary contraction (MVC) before intermittent maximal elbow flexor eccentric exercise, and two hours (2H), two days (2D) and four days (4D) post-exercise. Maximal voluntary force decreased by 21.3±5.6…
Facilitatory and inhibitory muscarine receptors on the rat phrenic nerve: effects of pirenzepine and dicyclomine
1988
Neuronal transmitter stores of the rat phrenic nerve were labelled by an incubation with [3H]choline. Release of [3H]acetylcholine was elicited either by a short (100 pulses, 5 Hz) or by a long (1500 pulses, 5 or 25 Hz) period of electrical nerve stimulation. Pirenzepine and dicyclomine enhanced transmitter release evoked by the short stimulation period. Both antagonists reduced transmitter release evoked by the long stimulation period. Pirenzepine reduced transmitter release at low concentrations (1 nmol/l) whereas a higher concentration was necessary for the enhancing effect; the opposite pattern was found for dicyclomine. A low concentration of oxotremorine (10 nmol/l) enhanced and a hig…
Online audio-visual information on oral cancer for Spanish-speaking laypersons. A cross-sectional study
2021
Background Lack of knowledge and awareness of oral cancer seem to be the main causes of diagnostic delay. Online resources are often used by patients to obtain health/medical information. However, there are no reports on the quality and usefulness of oral cancer audio-visual resources in Spanish. The aims of this investigation were to disclose the type of information about oral cancer available, and whether it may be useful to shorten the patients’ oral cancer appraisal time-interval. Material and Methods Cross-sectional study undertaken at three video-sharing sites on October, 13th 2019. Keywords: “Cáncer oral”; “cáncer de boca”. The first 100 results in each viewing list were retrieved by…
Effects of nicotine receptor agonists on acetylcholine release from the isolated motor nerve, small intestine and trachea of rats and guinea-pigs
1992
The effects of nicotine receptor agonists on the release of [3H]acetylcholine from the phrenic nerve, the small intestine and the trachea were investigated to characterize neuronal nicotine receptors within the peripheral nervous system. Contraction of the indirectly-stimulated hemidiaphragm was recorded to investigate desensitization of the postsynaptic muscular nicotine receptors. Nicotine, cytisine, 1,1-dimethyl-4-phenylpiperazinium and 2-(4-aminophenyl)-ethyl-trimethyl-ammoniumiodide caused a concentration-dependent (0.1-30 microM) increase in evoked [3H]acetylcholine release from the phrenic nerve, whereby bell-shaped concentration-response curves were obtained. The rank order of decre…
A transcranial magnetic stimulation study evaluating methylprednisolone treatment in multiple sclerosis
2002
Objective To investigate the efficacy of two different high doses of intravenous methylprednisolone (IVMP) during Multiple Sclerosis (MS) relapses. Background Transcranial Magnetic Stimulation (TMS) is the most sensitive neurophysiological ascertainment to quantify motor disability, to follow the recovery from an MS relapse, and to detect the response to treatment. Design and method Twenty-four clinically definite relapsing - remitting MS patients presenting a relapse were randomly assigned to a treatment for 5 days with IVMP 1 or 2 g/day. The response to treatment of each patient was evaluated through Expanded Disability Status Scale (EDSS), Medical Research Council (MRC) score, and TMS by…
Event-related potentials to task-irrelevant changes in facial expressions
2009
Abstract Background Numerous previous experiments have used oddball paradigm to study change detection. This paradigm is applied here to study change detection of facial expressions in a context which demands abstraction of the emotional expression-related facial features among other changing facial features. Methods Event-related potentials (ERPs) were recorded in adult humans engaged in a demanding auditory task. In an oddball paradigm, repeated pictures of faces with a neutral expression ('standard', p = .9) were rarely replaced by pictures with a fearful ('fearful deviant', p = .05) or happy ('happy deviant', p = .05) expression. Importantly, facial identities changed from picture to pi…
Functional relevance of presynaptic muscarinic autoreceptors.
1993
Pre- and postsynaptic muscarinic receptors have been characterized in the isolated trachea and ileal circular muscle of the guinea pig. The muscarinic autoreceptors mediating inhibition of acetylcholine release in the circular muscle belong to the M1 subtype, whereas those inhibiting acetylcholine release in the trachea are M2 or M4 receptors. In both tissues the postsynaptic muscarinic receptors are M3 receptors. Blockade of the autoreceptors by selective M1 and M2/M4 receptor antagonists leads to facilitation of cholinergic neurotransmission.
ERPs to pitch changes: a result of reduced responses to standard tones in rabbits.
1996
EVENT-RELATED potentials (ERPs) were recorded in rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, the deviant tones were presented without the standard tones (deviant-alone situation). In the oddball situation, significant difference ERPs (deviant ERPs - standard ERPs) could be found in the hippocampal and cerebellar recordings but not in the visual cortex. All the ERPs to the deviant stimuli observed in the oddball situation were also present in the deviant-alone situation. The difference ERPs were therefore based on reduced responses to the standards. The results are discussed in the context of a mismatch negativity (MMN) …