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Biomedical subjects

B Kamosińska

Publications and source records attributed to B Kamosińska.

5 recordsLinked to original sources

Spinal segmental sympathetic outflow to cervical sympathetic trunk, vertebral nerve, inferior cardiac nerve and sympathetic fibres in the thoracic vagus.

The spinal segmental localization of preganglionic neurons which convey activity to the sympathetic nerves, i.e. vertebral nerve, right inferior cardiac nerve, sympathetic fibres in the thoracic vagus and cervical sympathetic trunk, was determined on the right side in chloralose anaesthetized cats. For that purpose the upper thoracic white rami were electrically stimulated with a single pulse, suprathreshold for B and C fibres, and the evoked responses were recorded in the sympathetic nerves. The relative preganglionic input from each segment of the spinal cord to the four sympathetic nerves was determined from the size of the evoked responses. It was found that each sympathetic nerve receives a maximum preganglionic input from one segment of the spinal cord (dominant segment) and that the preganglionic input gradually decreased from neighbouring segments. The spinal segmental preganglionic outflow to the cervical sympathetic trunk, thoracic vagus, right inferior cardiac nerve and vertebral nerve gradually shifted from the most rostral to the most caudal spinal cord segments. In some cases, a marked postganglionic component was found in the cervical sympathetic trunk. It was evoked by preganglionic input from the same spinal cord segments which transmitted activity to the vertebral nerve. These results indicate that there is a fixed relation between the spinal segmental localization of preganglionic neurons and the branch of the stellate ganglion receiving the input from these neurons.

Animals↗

Neural control of airway pressures in rabbits.

In twenty anaesthetized and spontaneously breathing rabbits airway pressures were measured above and below the larynx during tidal respiration through the larynx. Peak inspiratory and expiratory pressures at both sites were recorded in control conditions and then compared to values obtained in the course of progressive denervation of the airways. The two methods of denervation consisted of (1) bilateral section of superior and recurrent laryngeal nerves and of the midcervical vagotomy (horizontal method); (2) right-sided sections of the three nerves followed by left-sided sections (vertical method). Motor denervation of the larynx due to RLNs neurotomy (horizontal method) produced significant increases in intratracheal pressures in both phases of the respiratory cycle. Less prominent increments in pressures were achieved on RLNs neurotomy in the vertical method. SLNs section and vagotomy had little additional effect on airway pressures. Our results indicate that unilateral laryngeal palsy poses far smaller obstruction to breathing than simultaneous bilateral denervation, and that afferent denervation of the larynx has no effect on airway pressures.

Animals↗

Effect of the larynx on ventilation and respiratory pattern in anesthetized rabbits.

The effects of the larynx on ventilation and pattern of breathing have been investigated in anesthetized, spontaneously breathing rabbits. Breathing was either via a tracheostomy or via a supralaryngeal tube in control condition, after laryngeal denervation and after subsequent bilateral midcervical vagotomy. Laryngeal resistance was measured in all experimental conditions when breathing was through the larynx. In control conditions the presence of the larynx in the breathing circuit, as compared to breathing through the tracheostomy, slightly but significantly lowered inspiratory and expiratory airflows, tidal volume, and minute ventilation and increased tracheal pressure. Inspiratory and expiratory durations were not significantly changed. Expiratory laryngeal resistance was higher than inspiratory. Laryngeal deafferentation did not significantly modify values of the respiratory variables. Subsequent motor denervation of the larynx enhanced the decrease in ventilatory parameters due to adding the larynx to the circuit and lengthened the respiratory cycle. Inspiratory laryngeal resistance increased sevenfold and expiratory resistance threefold. Subsequent midcervical vagotomy induced a further increase in inspiratory and expiratory durations and augmented tidal volume independent of the route of breathing, and also reduced laryngeal resistance previously increased by motor denervation. These results reveal the ventilatory effects of the larynx and show the importance of its patency in the pattern of breathing.

Airway Resistance↗

Phrenic output changes due to progressive airway denervation in rabbits.

The experiments were performed with thirteen anaesthetized rabbits breathing spontaneously through the larynx. Phrenic output was measured during tidal respiration in control conditions and in the course of progressive denervation of the laryngeal and tracheobronchial compartments. We have analysed changes in amplitude and the rate of rise of the integrated phrenic neurogram as well as the changes in TI, TE, TT and f of the respiratory timing after superior laryngeal nerves (SLN-s) section, section of the recurrent laryngeal nerves (RLN-s) and step-wise complete midcervical vagotomy. Nerve sections were performed by two methods: 1) bilateral SLN-s, RLN-s and cervical vagal neurotomy (horizontal method); 2) right-sided neurotomies of SLN, RLN and vagus followed by left-sided neurotomies of these nerves (vertical method). Laryngeal deafferentation did not greatly affect respiratory variables. Unilateral and especially bilateral vocal cord paralysis prolonged the respiratory cycle with enhanced TI/TT ratio, increased amplitude and rate of rise of the integrated phrenic neurogram. Maximum values of all parameters (the rate of rise excluded) were achieved after complete midcervical vagotomy. Of the two methods of denervation, the right-sided followed by left-sided denervation led to better adaptation of the organism to the respiratory disturbance (smaller changes in TI and TE compared with the control values). Denervation by the 'horizontal' method (paired section of the nerves) led to an abrupt failure of effective ventilation.

Animals↗