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H Gromysz

Publications and source records attributed to H Gromysz.

31 records · Page 2Linked to original sources
PubMed1976

Respiratory neurons of the ventral respiratory nucleus of the rabbit and their vagal connections.

The pattern of firing and responses to electrical stimulation of the ipsilateral vagus nerve were studied in respiratory neurons near the nucleus ambiguus (NA) in the region called "ventral respiratory nucleus". In 41 (out of 77) respiratory neurons orthodromic responses were recorded; the remaining neurons did not respond to stimulation. It is concluded that the NA neurons of the rabbit are not laryngeal motoneurons. Moreover, the short-latency excitatory response of some of these neurons, and long-latency inhibition of the other, suggest that NA neurons may be involved in the processing of vagal information.

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PubMed1973

Responses of respiratory neurons of the rabbit to some excitatory and inhibitory stimuli.

The effects of an afferent stimulation of the vagus nerve, hypercapnia and hyperventilation on the discharges of pontine, medullary and phrenic respiratory neurons were studied. The responses were investigated in spontaneously breathing, lightly anaesthetized rabbits with intact vagi, and subsequently during artificial ventilation, after vagotomy and under surgical anaesthesia. We found that the patterns of activity of respiratory neurons depend upon the integrity of vagal conduction, pattern of ventilation and depth of anaesthesia, and that vagotomy and deep anaesthesia markedly modify, and sometimes even reverse, the responses of these neurons to respiratory stimuli. The pre-vagotomy type of response can be restored by stimulating the central end of a cut vagus nerve with standard pulses triggered by action potentials recorded simultaneously from the animal respiratory unit. The significance of these findings is discussed.

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PubMedDate not supplied

Motor nucleus of the V-th nerve and the control of breathing. Breuer-Hering reflexes and apneustic breathing.

Earlier studies from this department have demonstrated that neurones of the V-th nerve motor nucleus (NVmt) have oligosynaptic, inhibitory output to the inspiratory motoneurone themselves under the influence of a polysynaptic input from vagal afferents. To check the hypothesis that NVmt is a part of the pneumotaxic mechanism, we studied the effects of pharmacological microblockade of the NVmt on Breuer-Hering reflexes in halothane-anesthetized, paralyzed and artificially ventilated rabbits. Activities of NVmt neurones and phrenic nerve firing were recorded. Acid-base balance was controlled and histologic examinations were routinely performed. Expiratory activities were regulatory found in NVmt. Its blockade elicited a typical apneustic breathing. During the blockade the Breuer-Hering reflexes gave "paradoxical" effects: an increase in central respiratory frequency following inflation, inspiratory apneusis in response to deflation. We conclude that the NVmt is an important component of the pneumotaxic mechanism or even the anatomical substrate of the pneumotaxic "centre".

Animals↗
PubMedDate not supplied

Studies on the mechanism of obstructive sleep apnea.

Several observations indicate that the mylohyoid nerve (NV) may play a crucial part in the mechanisms of obstructive sleep apnea (OSA). The activity of this nerve normally counteracts the collapse of the upper airways during inspiration. Any reduction in this activity may thus facilitate the occurrence of apnoeic spells. We have studied the effects of ethanol and lung inflations on the activity of NV recorded along with the activities of phrenic and facial nerve in rabbits anaesthetised with chloralose-urethan, paralyzed with curare and artificially ventilated. Under the control conditions the NV exhibited phasic expiratory activity; after vagotomy and additional, inspiratory component was observed. Lung inflation strongly enhanced the expiratory activity of NV whereas both the phrenic and facial nerve activities (both phasic-inspiratory) were typically inhibited. An injection of 5 ml of 20% ethanol very strongly inhibited the NV activity. The results may confirm the importance of NV in the mechanism of OSA. The well-known fact that OSA patients are particularly sensitive to alcohol finds support in the response of NV activity to ethanol injection. The analysis of the patterns of discharges of the three outputs from the respiratory controller may additionally suggest that the Vth nerve nucleus is involved in the control of respiratory pattern.

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