Motor control of pulmonary airways studied by nerve stimulation

Abstract

To investigate the motor control of the pulmonary airways we combined electrical stimulation of the cervical efferent vagus nerves of cats and dogs with measurement of pulmonary resistance (Rl) and anatomic dead space (Vd), and with anatomic study of rapidly frozen lungs. Stimulus frequencies between 1 and 12/sec produced almost the full range of Rl responses in eight cats. The major constrictor response to stimulation of one vagus nerve was in the lung of the same side in dogs and cats. A decrease of Vd associated with the increase of Rl in five cats during bilateral vagal stimulation suggested that the Rl change resulted from a generalized or large airway narrowing, rather than a local constriction. In seven cats whose lungs were frozen at end inspiration during unilateral vagal stimulation, the lobar bronchi on the stimulated side were smaller in diameter than comparable bronchi of the other side. In only two of seven cats was there definite constriction of the small cartilaginous and membranous airways of the stimulated side by the criterion of longitudinal mucosal ridges; in two there was slight constriction and in the other three, no change. Respiratory bronchioles and alveolar ducts of frozen sections were not constricted. pulmonary resistance; vagus nerve distribution; anatomy of pulmonary airways; vagus nerve impulse frequency; sympathetic nerve inhibition Submitted on May 1, 1964

The Quest for the Inhibitory Neurotransmitter in Bovine Tracheal Smooth Muscle

“…It is likely that some of the tracheal or bronchial dilatation observed during sympathetic nerve stimulation in intact animals such as dogs (Olsen, Colebatch, Mebel, Nadel & Staub, 1965) or guinea-pigs (Yip et al 1981) is mediated by catecholamines released from perivascular nerves and diffusing into the airways muscle layer.…”

Pulmonary neuronal M2 muscarinic receptor function in asthma and animal models of hyperreactivity

“…15 16 Physiological function of cholinergic nerves in the airways Stimulation of the parasympathetic nerves releases acetylcholine which causes the airway smooth muscle to contract, [15][16][17][18][19] the glandular tissue to secrete mucus, 20 21 and the bronchial circulation to dilate. 22 23 Studies both in man and in animals have shown that, in addition to causing contraction, the vagus nerves also maintain a baseline tonic contraction of the airway smooth muscle.…”

Neuronal muscarinic receptors attenuate vagally‐induced contraction of feline bronchial smooth muscle

“…It was especially important to know whether muscarinic receptors influence parasympathetic nerve activity in cat lung because this species has been used for many of the definitive studies on the dominant role of parasympathetic reflexes in the control of airway smooth muscle, (Daly & Mount, 1951;Widdicombe, 1954ab;Nadel et al, 1971;Olsen et al, 1965).…”

“…airway smooth muscle down to the level of the peripheral, respiratory bronchioles (Olsen et al, 1965;Nadel et al, 1971;Cabezas et al, 1971). In order to localize the neuronal muscarinic receptors within the airways, a method was chosen which recorded both lung resistance and dynamic lung compliance as these measurements reflect changes occurring mainly in the central and peripheral airways respectively (Widdicombe, 1963 Both vagi were tied and the distal ends stimulated simultaneously (10-20 V, 0.2 ms, 5-30 Hz, 300 pulses per train) at 5 min intervals with shielded platinium electrodes immersed in a pool of liquid paraffin.…”