Influence of bronchial C fibre receptors on respiration in cats: possible role in humans.
In order to find out whether the bronchial C fibre receptors influence respiration in cats, as the J receptors do, two drugs known to stimulate them consistently, i.e. phenyl diguanide (PDG) and capsaicin were injected into the left atrium (LA). The influence of these drugs, in suprathreshold doses, was seen on the intrapleural pressure (IPP), frequency of respiration (f(R)), systemic blood pressure (BP) and cardiac frequency (f(H)). PDG LA produced an inhibitory influence on respiration of a majority of cats, accompanied by a fall in BP and f(H). With capsaicin, a stimulation of respiration and a notable increase in BP (sometimes preceded by a fall also of f(H)) was seen. After blocking the epicardial/cardiac receptors with xylocaine, a local anaesthetic, the effects of PDG LA on the above variables were blocked, whereas, those of capsaicin survived--which they did, also after a bilateral vagotomy. Similar responses were obtained from injecting the drugs into the distal part of the aorta i.e. a notable stimulation of respiration by capsaicin, which survived vagotomy and hardly any effect, by PDG. It is concluded that activation of bronchial C fibre receptors does not influence respiration or BP in cats.
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Centre for Visceral Mechanisms, Vallabhbhai Patel Chest Institute, Delhi University, 110007, Delhi, India. apaa@iname.com
D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D016275:Atrial Function / Q000502:physiology; D001645:Biguanides / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi / Q000187:drug effects / Q000294:innervation*; D001981:Bronchial Arteries / Q000294:innervation / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D002415:Cats; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007267:Injections; D008012:Lidocaine / Q000494:pharmacology; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D015656:Respiratory Mechanics / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D014628:Vagotomy
D000779:Anesthetics, Local; D001645:Biguanides; D017366:Serotonin Receptor Agonists; D008012:Lidocaine; D002211:Capsaicin; C008846:phenyl biguanide