Aktionspotentiale atmungssynchron entladender Neurone der Medulla oblongata beim Husten

Engelhorn, R.; Weller, E.

doi:10.1007/bf00361631

Cited by 19 publications

(3 citation statements)

References 40 publications

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“…Weller (16,17) recorded the activity of expiratory neurons during coughs induced in anes thetized cats. They described that spikes of the expiratory neurons elicited by single shock to the SL nerve were abolished with 2 mg/ kg of codeine.…”

Section: Discussionmentioning

confidence: 99%

Effects of Antitussive Drugs on the Activity of the Recurrent Laryngeal Nerve in Cats

Mori¹,

Sakai²

1975

Jpn.J.Pharmacol

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Abstract-Reflex responses in the recurrent laryngeal (RL) nerve to stimulation of the superior laryngeal (SL) nerve and the effects of antitussive drugs on these reflex re sponses were studied in order to elucidate the site of action of these drugs in encephale isole cats. The RL nerve fibers were classified into four types by discharge patterns in respect to phases of artificial ventilation; type I: no spontaneous discharges, type II: discharges in phase with inflation of the lung, type III: discharges in phase with deflation of the lung, type IV: tonic discharges.Repetitive stimulation of the SL nerve elicited tonic burst discharges or short burst discharges in all types of RL nerve, while the same procedure inhibited ongoing discharges of the type III and IV fib: rs only. The inhibited fibers tended to have slow conduction velocities (20-80 m/sec). Administration of antitussive drugs such as codeine, dextro methorphan and oxymetebanol as well as pentobarbital decreased the frequency of the after spike dis chargesin the RL nerves evoked following repetitive shocks to the SL nerve, but had no effects on the inhibition of RL nerve discharges evoked by the stimulation of the same nerve. The neuropharmacological implication of these findings as related to the cough reflex are discussed.The special role of the glottis in the cough is well known (1). The glottis closes for a short time and then suddenly opens very early in the process of expiration. The activity in the recurrent laryngeal (RL) nerve either opens or closes the larynx through contraction of the corresponding musculatures (2, 3). Histological and physiological studies have shown that the ambigLius nucleus is the motor nucleus of the RL nerve (4, 5).In a previous report, a preliminary intracellular study of the ambiguus neurons was per formed and polysynaptic excitatory postsynatic potentials (EPSP) from the superior laryngeal (SL) nerve were recorded (6). However, the small size of the ambiguus motoneurons im peded the stable recording of the synaptic potentials responsible for the contraction of the glottis during repetitive stimulation of the SL nerve, thus making a quantitative assessment of the change during the time course of drug action almost impossible. Therefore, the present study was undertaken to obtain more information on the motoneurons by recording activity of the motor axons in the RL nerve which induce contraction of the laryngeal muscles and to ascertain the effects of certain antitussive drugs and pentobarbital on the RL nerve in cats.

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Section: Discussionmentioning

confidence: 99%

Effects of Antitussive Drugs on the Activity of the Recurrent Laryngeal Nerve in Cats

Mori¹,

Sakai²

1975

Jpn.J.Pharmacol

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“…Recently Morest reported that the STN neurons have synaptic connections with the nucleus ambiguus and its adjacent regions (14). Engelhorn and Weller have shown that ambiguus neurons discharge tonically during the SL nerve stimulation in cats (15,16). It may be conceivable that some of the neurons in and around the nucleus ambiguus play an important role in the cough reflex.…”

Section: Methodsmentioning

confidence: 99%

Re-Examination of Centrally-Induced Cough in Cats Using a Micro-Stimulation Technique

Mori

Sakai

1972

Jpn.J.Pharmacol

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The results indicate that the area, in which the cough-like response is produced by electrical stimulation, is confined distinctly to a certain anatomical structure of the me dulla, i.e., the nucleus tractus solitarius. METHODSTwenty cats, weighing 2.5-3.5 kg, were used. These were anesthetized with ether under open drop method and fixed with the aid of a stereotaxic instrument. An occipital crani otomy was performed to expose the cerebellum, and portions of the cerebellum covering the medulla were removed by suction. Immediately after the surgical operation, ether inhalation was discontinued and the animal was kept under light anesthesia with pentobarbital sodium (15 mg/kg i.v.) alone. The trachea was cannulated at the level below the cricoid cartilage. The internal branche of the superior laryngeal nerve (SL nerve) was cut bilaterally at the entrance to the larynx and was separated carefully from surrounding tissues about 3 cm long up to the nodose ganglion. The distal end of each was ligated with a cotton thread and tied to the distal lead of a collar-type electrode implanted for stimulation and recording. A monopolar tungsten microelectrode (electrolytically polished, about 2/t in diameter at the tip, insulated with polyurethane) was used for stimulation of the medulla. A silver-silverchlo ride plate was fixed at the neck muscle and was used as an indifferent electrode. The micro

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“…Models of the former type are exemplified by, e.g., electrical stimulation of the dorso-lateral area of the medulla oblongata [5], by transverse sectioning of the brain-stem [10], or by picking up distinct electrical activities in the intracentral respiratory areas during cough [11]. Our models are of the indirect type.…”

Section: The Central Part Of the Reflexmentioning

confidence: 99%

Cough and antitussives: Considerations and experiments

Bücher

1974

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Whenever pharmacologists work experimentally on cough and antitussives, they will clearly distinguish between their aim and their tools. The aim, at least the final one, will in some way or other be the clinical process denominated as cough. And the tools will be models, which may represent partial but actual elements of a clinical cough or even hypothetical elements only. An artificially induced bronchogenic seizure of expiratory thrusts in cats is an example of the former type; the models 1-3 as described in this paper ar examples of the latter.There is always a gap between the clinical cough and the parameters of the model. The more closely the model will imitate the clinical phenomenology, the higher will be the probability that a substance screened out with the model will be of some therapeutic value -the smaller, however, will be the chance to know why. On the other hand, with models which focus on dements which are only potentially relevant for the clinical process of coughing, a prediction as to the clinical usefulness will be less certain; a gain in scientific information, however, will be more or less guaranteed. Both kinds of approach may be useful. As for us, we like the more scientific one better than the more empirical one.

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Aktionspotentiale atmungssynchron entladender Neurone der Medulla oblongata beim Husten

Cited by 19 publications

References 40 publications

Effects of Antitussive Drugs on the Activity of the Recurrent Laryngeal Nerve in Cats

Effects of Antitussive Drugs on the Activity of the Recurrent Laryngeal Nerve in Cats

Re-Examination of Centrally-Induced Cough in Cats Using a Micro-Stimulation Technique

Cough and antitussives: Considerations and experiments

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