1. The effects of asphyxia, hypoxia, hypercapnia, stimulation of peripheral chemoreceptors, pneumothorax and breathing through resistances have been investigated on laryngeal resistance to airflow in anaesthetized cats, with and without bilateral vagotomy below the origin of the recurrent laryngeal nerves.2. Resistance to airflow of the innervated larynx was usually measured with the larynx isolated in situ with constant flow from the trachea to a pharyngeal opening, and expressed by the relationship between translaryngeal pressure and airflow.3. Asphyxia, hypoxia and hypercapnia each stimulated breathing and decreased laryngeal resistance to airflow, in both the inspiratory and expiratory phases. After vagotomy the effect was reduced, abolished or (usually) reversed to a laryngeal constriction, especially in expiration.4. Intra-arterial injections of potassium cyanide (to stimulate carotid body chemoreceptors) caused a short apnoea or an augmented breath followed by hyperpnoea, concurrently with expiratory constrictions of the larynx. The responses were usually stronger after bilateral vagotomy.5. Pneumothorax caused tachypnoea, inspiratory dilatations and expiratory constrictions of the larynx. The responses were abolished by vagotomy.6. Imposition of respiratory resistances dilated the larynx, in inspiration and expiration, while complete closure of trachea caused expiratory constrictions of the larynx. These changes did not depend on intact vagal pathways.7. The results are discussed in terms of nervous control of the larynx in the different conditions.

Airway Resistance↗

PubMed1974

Changes in laryngeal calibre due to inhalation of dust.

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Abdominal Muscles↗

PubMed1974

Viral infection and lipemia: a problem of disordered host physiology.

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Animals↗

PubMed1974

Orthotics.

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Humans↗

PubMed1973

The modern ankle-foot orthoses (AFO's).

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Acrylates↗

PubMed1972

The graphical determination of K m and K i .

The principle of Dixon (1965) has been extended to give rapid graphical methods for determining enzyme constants for substrates (K(m)) and inhibitors (K(i)). It does away with the sometimes questionable assumption that the amounts of substrate or inhibitor bound by the enzyme are negligible in comparison with the total amount added, and is therefore valid even for cases of high affinity, where the usual methods fail. Besides doing away with the need for calculation, it enables the concentrations of the various components of the system to be read off directly for any point of the velocity curve.

Enzyme Inhibitors↗

PubMed1971