Apnoeic responses to intracarotid nicotine challenge in anaesthetized cats.

To determine the effects of an intraarterial administration of nicotine on the occurrence of apnoea and the activity of rib cage respiratory muscles, we studied 31 anaesthetized, spontaneously breathing cats. Phrenic activity was used as an index of neural inspiratory drive. Activity of parasternal intercostal (PIM) and triangularis sterni (TS) muscles was recorded. Nicotine in a dose of 65 microg/kg was injected into the left common carotid artery prior to and after midcervical vagotomy, preceded by section of the superior laryngeal nerves (SLNs). In eight additional cats, initially neurotomized as mentioned, nicotine was injected after bilateral disruption of the carotid sinus nerves (CSNs). Nicotine induced prompt expiratory apnoea of mean duration of 5.4+/-0.3s in 19 non-vagotomized and of 5.92+/-0.51 s (mean+/-S.E.M.) in 13 vagotomized cats. The occurrence and duration of the temporary arrest of breathing were reduced by midcervical vagotomy but not by subsequent CSNs neurotomy, which abolished post-apnoeic acceleration of breathing. In post-nicotine breathing of increased tidal volume and respiratory rate, peak activity of the parasternal intercostal muscles increased from baseline of 3.2+/-1.2 to 9.5+/-2.0 arbitrary units (p<0.001). The peak height of the phrenic nerve elevated from 7.9+/-0.9 to 14.5+/-1.7 arbitrary units (p<0.001). That of the triangularis sterni showed no change. The response of the respiratory effectors elicited by nicotine was independent of the vagal integrity and may be attributed to activation of nicotine receptors within the brainstem respiratory neurones.

Diverging respiratory effects of serotonin and nicotine in vagotomised cats prior to and after section of carotid sinus nerves.

Respiratory effects of intravenous serotonin and nicotine were investigated prior to and after bilateral neurotomy of the carotid sinus nerves (CSNs) in eight pentobarbitone/chloralose-anaesthetised, bilaterally vagotomised and superior laryngeal nerves-sectioned cats. Injection of 188 nmol kg(-1) serotonin (hydrogen oxalate salt, 50 microg x kg(-1)) prior to and after CSNs section induced an expiratory apnoea of, respectively, 7.9 +/- 1.25 s and 8.3 +/- 1.6 s duration (mean +/- S.E.M.) in, respectively, five and three of those cats. In all cats, the serotonin challenge produced a period of accelerated breathing (P < 0.05) both prior to and after section of CSNs. Injection of a 433 nmol nicotine bolus (hydrogen tartrate salt, 200 microg) increased tidal volume by 25 +/- 8% in cats with intact CSNs (P < 0.01), but decreased it by 13 + 10% (P < 0.05) after CSNs section. Nicotine, but not serotonin, transiently increased mean arterial blood pressure in our cats, which rise was delayed by CSNs cut. Results of this study indicate that the respiratory response to serotonin occurs beyond carotid body chemoreceptors in vagotomised cats, and suggest that the volume response to intravenous nicotine depends qualitatively on carotid body chemoreceptor input in this experimental model.

Response of respiratory muscles to intravenous nicotine challenge in anaesthetized cats.

The effects of an intravenous nicotine challenge on the ventilation and activity of rib cage muscles were studied in 33 pentobarbitone-chloralose anaesthetized cats. Bolus injection of nicotine (200 microg) into the right femoral vein evoked in 19 of the intact animals prompt, short-lived apnoea, or prolongation of the first expiration after the drug, the occurrence of which was significantly reduced by midcervical vagotomy (P < 0.001). In breaths that followed the apnoea, peak activity of the parasternal intercostal muscles increased from a baseline of 3.1 +/- 0.8 to 9.2 +/- 1.8 arbitrary units (P < 0.001). Nicotine produced a similar increase in peak phrenic ENG (7.0 +/- 0.5 to 14.5 +/- 1.2 arbitrary units; P < 0.001). Peak triangularis sterni muscle EMG was reduced from 8.9 +/- 1.2 to 6 +/- 1.7 arbitrary units (P < 0.05) and the onset of response was delayed to 30 s after the challenge. The changes of respiratory effectors induced by nicotine were independent of vagal integrity. The results show that post-nicotine apnoea is to large extent vagally dependent though the response of the respiratory muscles is mediated by non-vagal influences.

Apnoeic responses to pulmonary and systemic challenge of capsaicin in cats.

The contribution of sensory laryngeal and pulmonary inputs to expiratory apnoea and post-apnoeic breathing induced by capsaicin given to pulmonary circulation and to aortic arch was studied in the anaesthetized, spontaneously breathing, normoxic cats. Breathing was via tracheostomy. Capsaicin (10 micrograms (kg body wt)-1) was injected intravenously and to the aortic arch in the intact animal, then after section of the superior laryngeal nerves, and finally after midcervical vagotomy. Capsaicin, injected as a bolus, induced expiratory arrest of breathing on both ways of injection, larger and vagally dependent (P < 0.05) on intravenous route, and apparently disparate in ventilatory sequence from the systemic challenge. Tidal volume was affected in the opposite direction on either route and the respiratory rate increased significantly more with an intravenous administration (P < 0.01). Bilateral section of the cervical vagi virtually abolished the effects of capsaicin on the breathing pattern independent of the site of challenge.

Action of serotonin on the laryngeal airway in anaesthetized cats.

The pulmonary chemoreflex induced by an intravenous injection of serotonin (5-hydroxytryptamine) in cats consists of prompt apnoea, bradycardia and hypotension, followed by rapid, shallow breathing. The present study had two purposes (1) to compare the effect of 5HT on ventilation and laryngeal resistance in cats and (2) to assess the role of laryngeal afferents in these responses. The effects of an intravenous injection of serotonin at a dose of 0.05 mg per kg of body weight were studied in eighteen anaesthetized cats, breathing spontaneously via a tracheal cannula. In eleven cats the larynx was isolated in situ to measure laryngeal resistance. In post-serotonin apnoea, the expiratory laryngeal resistance rose four-fold. This coincided with the increased afferent activity of the superior laryngeal nerve. In the initial phase of resumed shallow breathing, the increase in the expiratory laryngeal resistance was coupled with reduced tidal volume. Bilateral section of the superior laryngeal nerve failed to affect laryngeal constriction and the ventilatory response to serotonin. Thus laryngeal afferents running within the superior laryngeal nerve are not essential for the respiratory phenomena induced by serotonin.

[Dietary pattern of workers employed in a 3-shift system]. / Sposób zywienia robotników zatrudnionych w systemie trójzmianowym (badania pilotazowe).

The studies were performed among 105 workers aged 19 to 30 years, working in a 3-shift-system for at least one year. A questionnaire method of examination was used. Each worker was asked about his usual frequency of meals, sleep time and life routine while working on different shifts, as well as about the consumption of food in the last 24 hours. Usually, regardless of the period of working shift, workers consumed few number 57 meals. Meals during the working time were eaten mostly by morning-shift workers and very rarely by night-shift workers. Comparing calorific values of the meals consumed prior to the working hours at different time of shift work it has been shown that the meals consumed before night shift had the highest values, whereas the meals consumed prior to the morning shift had the lowest values. Generally, the meals consumed by shift workers did not vary and involved a large percentage of meat products, and fats, and too little percentage of vegetables, fruit, milk and dairy products. The food consumed by the workers under examinination contained mainly fats, protein and relatively little carbohydrates and ascorbic acid. Most of the workers preferred morning shift although sleep time was longest in case of afternoon shift. Complaints typical of the night shift included great fatigue and sleepiness. The sleep time was the shortest in case of this shift and sometimes it hardly amounted to 3 hours per day. The obtained results may be used for an elaboration of the lines of most suitably arranged meals schedule for shift and night workers.