Mechanisms of Nerve Impulse Initiation in a Pressure Receptor (Lorenzinian Ampulla)

Nature ◽  
1960 ◽  
Vol 188 (4755) ◽  
pp. 1034-1035 ◽  
Author(s):  
WERNER R. LOEWENSTEIN
Keyword(s):  
Nerve Impulse ◽  
Pressure Receptor

XRF and PIXE Analysis of light and Dark Adapted Ocular Tissue

1982 ◽  
Vol 40 ◽  
pp. 190-191
Author(s):  
B. J. Panessa ◽  
H. W. Kraner ◽  
J. B. Warren ◽  
K. W. Jones
Keyword(s):  
Trace Metals ◽  
Pigment Epithelium ◽  
Nerve Impulse ◽  
Light Response ◽  
Ocular Tissue ◽  
Emission Spectrometry ◽  
Retinol Dehydrogenase ◽  
Pixe Analysis ◽  
X Ray ◽  
Optimal Function

During photoexcitation the retina requires specific electrolytes and trace metals for optimal function (Na, Mg, Cl, K, Ca, S, P, Cu and Zn). According to Hagins (1981), photoexcitation and generation of a nerve impulse involves the movement of Ca from the rhodopsin-ladened membranes of the rod outer segment (ROS) to the plasmalemma, which in turn decreases the in-flow of Na into the photoreceptor, resulting in hyperpolarization. In toad isolated retinas, the presence of Ba has been found to increase the amplitude and prolong the delay of the light response (Brown and Flaming, 1978). Trace metals such as Cu, Zn and Se are essential for the activity of the metalloenzymes of the retina and retina pigment epithelium (RPE) (i.e. carbonic anhydrase, retinol dehydrogenase, tyrosinase, glutathione peroxidase, superoxide dismutase...). Therefore the content and fluctuations of these elements in the retina and choroid are of fundamental importance for the maintenance of vision. This paper presents elemental data from light and dark adapted frog ocular tissues examined by electron beam induced x-ray microanalysis, x-ray fluorescence spectrometry (XRF) and proton induced x-ray emission spectrometry (PIXE).

Review about structure and evaluation of reactivators of Acetylcholinesterase inhibited with neurotoxic organophosphorus compounds

2020 ◽  
Vol 27 ◽  
Author(s):  
José Daniel Figueroa-Villar ◽  
Elaine C. Petronilho ◽  
Kamil Kuca ◽  
Tanos C. C. Franca
Keyword(s):  
Organophosphorus Compounds ◽  
Chemical Warfare Agents ◽  
Nerve Impulse ◽  
Limited Capacity ◽  
New Agents ◽  
Long Time ◽  
Warfare Agents ◽  
Comprehensive Search ◽  
Pharmacology And Toxicology ◽  
The Many

Background: Neurotoxic chemical warfare agents can be classified as some of the most dangerous chemicals for humanity. The most effective of those agents are the organophosphates (OPs) capable of restricting the enzyme acetylcholinesterase (AChE), which in turn controls the nerve impulse transmission. When AChE is inhibited by OPs, its reactivation can be usually performed through cationic oximes. However, until today it has not been developed one universal defense agent, with complete effective reactivation activity for AChE inhibited by any of the many types of existing neurotoxic OPs. For this reason, before treating people intoxicated by an OP, it is necessary to determine the neurotoxic compound that was used for contamination, in order to select the most effective oxime. Unfortunately, this task usually requires a relative long time, raising the possibility of death. Cationic oximes also display a limited capacity of permeating the blood-brain barrier (BBB). This fact compromises their capacity of reactivating AChE inside the nervous system. Methods: We performed a comprehensive search on the data about OPs available on the scientific literature today in order to cover all the main drawbacks still faced in the research for the development of effective antidotes against those compounds. Results: Therefore, this review about neurotoxic OPs and the reactivation of AChE, provides insights for the new agents’ development. The most expected defense agent is a molecule without toxicity and effective to reactivate AChE inhibited by all neurotoxic OPs. Conclusion: To develop these new agents it is necessary the application of diverse scientific areas of research, especially theoretical procedures as computational science (computer simulation, docking and dynamics); organic synthesis; spectroscopic methodologies; biology, biochemical and biophysical information; medicinal chemistry, pharmacology and toxicology.

scholarly journals NERVE IMPULSE

1904 ◽  
Vol 31 (2) ◽  
pp. 139
Author(s):  
JELLIFFE
Keyword(s):  
Nerve Impulse

Mechanoreceptor afferent activity compared with receptor field dimensions and pressure changes in feline urinary bladder

1992 ◽  
Vol 70 (11) ◽  
pp. 1457-1467 ◽  
Author(s):  
John W. Downie ◽  
J. Andrew Armour
Keyword(s):  
Contractile Activity ◽  
Bladder Wall ◽  
Afferent Activity ◽  
Intravesical Pressure ◽  
Receptor Field ◽  
Precise Relationship ◽  
Pressure Changes ◽  
The Relationship ◽  
Simple Fashion ◽  
Pressure Receptor

The relationship between vesical mechanoreceptor field dimensions and afferent nerve activity recorded in pelvic plexus nerve filaments was examined in chloralose-anesthetized cats. Orthogonal receptor field dimensions were monitored with piezoelectric ultrasonic crystals. Reflexly generated bladder contractile activity made measurements difficult, therefore data were collected from cats subjected to actual sacral rhizotomy. Afferent activity was episodic and was initiated at different pressure and receptor field dimension thresholds. Maximum afferent activity did not correlate with maximum volume or pressure. Furthermore, activity was not linearly related to intravesical pressure, receptor field dimensions, or calculated wall tension. Pressure–length hysteresis of the receptor fields occurred. The responses of identified afferent units and their associated receptor field dimensions to brief contractions elicited by the ganglion stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (2.5–20 μg i.a.), studied under constant volume or constant pressure conditions, are compatible with bladder mechanoreceptors behaving as tension receptors. Because activity generated by bladder mechanoreceptors did not correlate in a simple fashion with intravesical pressure or receptor field dimensions, it is concluded that such receptors are influenced by the viscoelastic properties of the bladder wall. Furthermore, as a result of the heterogeneity of the bladder wall, receptor field tension appears to offer a more precise relationship with the activity of bladder wall mechanoreceptors than does intravesical pressure.Key words: bladder distension, intravesical pressure, sacral rhizotomy, viscoelasticity.

scholarly journals Molecular Bases for the Asynchronous Activation of Sodium and Potassium Channels Required for Nerve Impulse Generation

Neuron ◽  
2013 ◽  
Vol 79 (4) ◽  
pp. 651-657 ◽  
Author(s):  
Jérôme J. Lacroix ◽  
Fabiana V. Campos ◽  
Ludivine Frezza ◽  
Francisco Bezanilla
Keyword(s):  
Potassium Channels ◽  
Nerve Impulse ◽  
Impulse Generation ◽  
Molecular Bases ◽  
Sodium And Potassium

Facilitation at the Lobster Neuromuscular Junction: A Stimulus-Dependent Mobilization Model

1997 ◽  
Vol 78 (1) ◽  
pp. 417-428 ◽  
Author(s):  
Mary Kate Worden ◽  
Maria Bykhovskaia ◽  
John T. Hackett
Keyword(s):  
Neuromuscular Junction ◽  
Kinetic Equations ◽  
Nerve Impulse ◽  
Stimulation Frequency ◽  
Synaptic Activity ◽  
Quantal Content ◽  
Physiological Basis ◽  
Low Frequencies ◽  
Average Probability ◽  
Frequency Facilitation

Worden, Mary Kate, Maria Bykhovskaia, and John T. Hackett. Facilitation at the lobster neuromuscular junction: a stimulus-dependent mobilization model. J. Neurophysiol. 78: 417–428, 1997. Frequency facilitation is a process whereby neurosecretion increases as a function of stimulation frequency during repetitive synaptic activity. To examine the physiological basis underlying facilitation, we have estimated the frequency dependence of the synaptic parameters n (number of units capable of responding to a nerve impulse) and P (average probability of responding) at the lobster neuromuscular junction. Both n and P increase as a function of frequency, suggesting that the efficiency of quantal docking and quantal fusion is regulated by repetitive synaptic activity. In experiments in which facilitation is strong and quantal content does not saturate over the frequency range tested, the value of P saturates at low frequencies of stimulation, and increases in quantal content at higher frequencies of stimulation are due to an increase in n. Therefore the value of P does not limit facilitation. We propose that transmitter release is limited by the rates of quantal mobilization and demobilization, and that each excitatory stimulus causes additional mobilization of quanta to dock at the presynaptic release sites. In such a model the binomial parameter n will correspond to the number of quanta docked at the release sites and available for release. We have developed and solved kinetic equations that describe how the number of docked quanta changes as a function of time and of stimulation frequency. The stimulus-dependent mobilization model of facilitation predicts that the reciprocal value of the quantal content depends linearly on the reciprocal product of the stimulation frequency and the probability of release. Fits of the experimental data confirm the accuracy of this prediction, showing that the model proposed here quantitatively describes frequency facilitation. The model predicts that high rates of quantal demobilization will produce strong frequency facilitation.

The Evolution of the Colour Sense

1901 ◽  
Vol 47 (199) ◽  
pp. 678-679
Author(s):  
F. W. Edridge-Green
Keyword(s):  
Nerve Impulse ◽  
The Other ◽  
Physiological Basis ◽  
Black And White ◽  
Normal Distance ◽  
Colour Sense ◽  
Two Factors ◽  
Colour Blindness ◽  
The Mind

All the facts which can be gathered from the study of museums or literature point to the conclusion that the sense of light was developed first, then the sense of colour. The tendency has been to regard colour-blindness as “chromic myopia;” but this is not correct unless there is a defective perception of light as well, as shown by the cases which I have recorded. A man may be able to see light of all colours at twice the normal distance, and yet be colour-blind. I specially wish to emphasise the fact that there is no definite relation between light and colour. When light falls upon the eye it sets up a nerve impulse, which is conveyed to the brain. In the impulse itself we have the physiological basis of light, and in the quality of the impulse the physiological basis of colour. My contention is that these two factors are perceived by two entirely different sets of cerebral cells, those devoted to the perception of colour being developed at a later period than those conveying to the mind the sensation of light. All the evidence which can be obtained shows that all objects were first seen as in a photograph, that is, in different degrees of black and white. In the evolution of the colour sense those waves which differ most physically, namely, red and violet, were first recognised as different, the remainder of the spectrum appearing grey. Homer's colour vision was of this class, which represents the degree just preceding total colour-blindness. I have recorded a case of this kind of a man who was colour-blind with one eye, and who was therefore able to tell me exactly how objects appeared with this eye. He said that the spectrum appeared nearly all grey, but with a tinge of red at one end and a tinge of violet at the other; he could see very much better with the colour-blind eye than with the other.

Adrenolytic and sympatholytic action of certain dihydrogenated ergot alkaloids (Hydergine) on dog kidney

1960 ◽  
Vol 15 (1) ◽  
pp. 109-114
Author(s):  
W. G. Kubicek
Keyword(s):  
Blood Pressure ◽  
Body Weight ◽  
Blood Sugar Level ◽  
Ergot Alkaloids ◽  
Nerve Impulse ◽  
Intravenous Dose ◽  
Renal Nerves ◽  
Induced Hypertension ◽  
Dog Kidney ◽  
Sympatholytic Action

Adrenolytic action of dihydrogenated (DH) ergot alkaloids was estimated in denervated dog kidneys and the sympatholytic action was estimated on electrically stimulated renal nerves. Blood sugar level, hematocrit, blood pressure and pulse rate were observed in most of the experiments. The minimal effective intravenous dose of Hydergine or its components to block the epinephrine vasoconstriction in the denervated kidneys was approximately 3.5 μg/kg of body weight while a somewhat larger dose was required to block sympathetic nerve impulse transmission. Oral administration of these alkaloids required a dosage approximately ten times the minimal effective intravenous dose. The DH ergot alkaloids reduced the epinephrine-induced hypertension and had little if any effect upon the hyperglycemia and elevated hematocrit observed during continuous epinephrine infusions. Submitted on May 29, 1959

Sign in / Sign up

Export Citation Format

Share Document