Characteristics of augmented breaths provoked by almitrine bismesylate in cats

Abstract

SUMMARYThe contribution of almitrine bismesylate to the occurrence and pattern of augmented breaths was studied in fifteen spontaneously breathing, anaesthetized cats. Breathing was via a tracheostomy, while the laryngeal resistance to airflow was measured with the larynx isolated in situ.Almitrine bismesylate at a dose of 0 5 mg kg-1 of body weight was injected intravenously in the intact animals and following bilateral vagotomy which spared the right recurrent laryngeal nerve. Almitrine injected intravenously elicited augmented breaths within the first 45 s in thirteen cats and within 1 min in the remaining two cats. During augmented breaths inspiratory and expiratory airflows rose, the mean increases being 385 2 and 159-6 % respectively above the controls (P < 0 01).The inspiratory laryngeal resistance declined to 77-7 % of the control (P < 0 01) and expiratory laryngeal resistance increased by 954 % above the control level (P < 001). The inspiratory and expiratory times were prolonged by 56 and 580% compared with baseline breathing. Following the augmented breaths the respiratory airflows exceeded baseline values, the respiratory timing was slightly reduced, and the inspiratory laryngeal resistance was significantly lowered below the control level (P < 0-01). The expiratory laryngeal resistance showed the same trend without statistical significance. Bilateral vagotomy abolished the occurrence of augmented breaths following almitrine injection.

Effects of the hippocampus on the motor expression of augmented breaths

“…In the current study, low amplitudes in the first few breaths after an augmented breath (between 1–5 breaths) were typical but with a gradual return to normal breathing cycles after approximately 4–5 breathes. This consistent characteristic is similar to augmented breaths that were evoked by stimulating peripheral chemoreceptors using almitrine [ 42 ]. In the case of almitrine-induced augmented breaths, post-augmented breaths were characterised by diminished airflow.…”

Limbic modulation of the autonomic nervous system

“…In the current study low amplitudes in the first few breaths after an augmented breath (between 1 -5 breaths) were typical but with a gradual return to normal breathing cycles after approximately 4 -5 breathes. This consistent characteristic is similar to augmented breaths that were evoked by stimulating peripheral chemoreceptors using almitrine (Szereda-Przestaszewska et al, 1992). In the case of almitrine-induced augmented breaths, post-augmented breaths were characterised by diminished airflow.…”

Oxygen Sensing

“…The present work was supported by grants-inaid 08670028 and 09670022 from the Ministry of Education, Science and Culture, Japan. The breaths immediately following a sigh are more rapid and shallow compared to the pre-sigh breaths (Szereda-Przestaszewska et al, 1992). Phase 2 has a greater inspiratory trajectory, is approximately twice the size of phase 1 and begins at the peak of phase 1 (i.e.…”