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Biomedical subjects

J C Wise

Publications and source records attributed to J C Wise.

9 recordsLinked to original sources
PubMed1978

Lung reflexes in rabbits during pulmonary stretch receptor block by sulphur dioxide.

Anaesthetized rabbits were given 200 ppm sulphur dioxide to breathe for 10 min. This abolished activity in 23 of 26 pulmonary stretch receptors, while leaving that of lung irritant receptors unimpaired. The Breuer-Hering reflex was abolished and breathing became deeper and slower. Inspiratory time (tI) was increased and expiratory time (tE) decreased. Subsequent vagotomy increased tidal volume (VT), tI and tE. In animals with stretch receptors blocked, injections of phenyl diguanide and histamine still increased breathing frequency and decreased VT, indicating that reflexes from lung irritant and J-receptors were intact. Inhalation of 8% CO2 caused a bigger increase in frequency and tidal volume in rabbits with stretch receptor block compared with controls or those after vagotomy. Induction of pneumothorax with stretch receptor block transiently prolonged tI and shortened tE; removal of the pneumothorax also transiently shortened tE and usually also decreased tI. The results suggest that lung irritant receptors reflexly shorten tE in all our experimental conditions, but have various effects on tI which may depend on the timing of the irritant receptor discharge and refractoriness of the inspiratory response.

Animals↗
PubMed1976

Changes in respiratory frequency and end-expiratory volume accompanying augmented breaths in cats.

We have studied the pattern of breathing before, during and after augmented breaths in spontaneously breathing, anesthetized cats with the larynx both in and out of the breathing circuit. Following augmented breaths we consistently observed increases in end-expiratory lung volume (EEV), end-expiratory transpulmonary pressure, dynamic lung compliance and respiratory frequency. These changes were of similar magnitude whether the larynx was in or out of circiut and were uninfluenced by section of the superior laryngeal nerves. Laryngeal resistance, measured under constant flow conditions with the larynx removed from the breathing circuit, showed an exaggerated inspiratory decrease during augmented breaths. Passive lung inflations, performed so as to mimic the pattern of augmented breaths, increased dynamic lung compliance but did not elicit changes in EEV or respiratory frequency. The results indicate that the increase in EEV cannot be attributed to increased lung compliance but results from a change in end-expiratory respiratory muscle tone. This change, and the change in respiratory frequency appear to be part of a reflexly evoked central response that includes the augmented breath itself. The larynx participates in the augmented breath, but its mechanical importance is small.

Airway Resistance↗
PubMed1976

Location of stretch receptors in the trachea and bronchi of the dog.

1. Using single fibre vagal afferent recording techniques, we have investigated the longitudinal and circumferential location of slowly adapting stretch receptors in a functionally isolated, in situ segment of the trachea in dogs. 2. We have also studied the depth of these receptors within the airway wall and their response to reflex and drug induced contraction of the airway smooth muscle. 3. Thirty-four per cent of the receptors studied were in the extrathoracic trachea; calculations indicate that about 17-1% of all airway stretch receptors lie outside the thorax. 4. All the receptors were located in the membranous posterior wall of the trachea, and those tested responded more to transverse than to longitudinal stretching of the wall. 5. Receptors in the extrathoracic trachea continued to function after the regional mucosa had been widely resected; subsequent removal of histolocially proven smooth muscle tissue caused the abrupt cessation of receptor discharge. 6. Contraction of airway smooth muscle brought about an increase in receptor discharge frequency. 7. Similar results were found for a smaller number of stretch receptors located in the mainstem and lobar bronchi. 8. These findings procided evidence that stretch receptors are anatomically located within the smooth muscle layer of the airways and are functionally aranged in series with the muscle fibres.

Action Potentials↗
PubMed1976

Transduction properties of tracheal stretch receptors.

1. Using single fibre vagal afferent recording, we have studied the behavior of slowly adapting stretch receptors located in an isolated, in situ, segment of the trachea in dogs. Responses to positive and negative steady and oscillating transmural pressures were investigated. 2. Seventy-eight per cent of the receptors studied were tonically active at resting tracheal volume. Ninety per cent showed a more pronounced response to positive than to negative transmural pressures. 3. During pressure oscillations the majority of the receptors had a higher discharge frequency at any given pressure during the ascending phase of the pressure wave than at the same pressure under static conditions. During most of the ensuing descent of pressure toward zero the discharge frequency led transmural pressure. 4. With increasing frequency of oscillation the differences from the static responses increased (dP/dt sensitivity), especially during the ascending limb of the pressure oscillation (rectifying behavior). 5. In a small number of receptors, discharge frequency lagged behind transmural pressure or was in phase with it ("no loop" pattern). 6. In three cases the same receptor exhibited dP/dt sensitivity during positive pressure oscillations, whereas discharge frequency lagged behind pressure during negative pressure oscillations. This indicates that the lack of dP/dt sensitivity exhibited under negative pressure conditions does not represent an intrinsic property of these receptors, but reflects some aspect of their mechanical arrangement within the airway wall. 7. THESE PATTERNS OF RESPONSE ARE DISCUSSed in terms of intrinsic and extrinsic characteristics of the receptors. 8. The physiological implications of stretch receptor behaviour are also considered.

Action Potentials↗