Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the contribution of vagal airway receptors to ventilatory control during hypercapnia, we studied 11 normal humans. Airway receptor block was induced by inhaling an aerosol of lidocaine; a preferential upper oropharyngeal block was also induced in a subgroup by gargling a solution of the anesthetic. Inhalation of lidocaine aerosol adequate to increase cough threshold, as measured by citric acid, did not change the ventilatory response to CO2, ratio of the change in minute ventilation to change in alveolar PCO2 (delta VI/delta PACO2), compared with saline control. Breathing pattern at mean CO2-stimulated ventilation of 25 l/min showed significantly decreased respiratory frequency, increased tidal volume, and prolonged inspiratory time compared with saline. Resting breathing pattern also showed significantly increased tidal volume and inspiratory time. In nine of the same subjects gargling a lidocaine solution adequate to extinguish gag response without altering cough threshold did not change delta VI/delta PACO2 or ventilatory pattern during CO2-stimulated or resting ventilation compared with saline. These results suggest that lower but not upper oropharyngeal vagal airway receptors modulate breathing pattern during hypercapnic as well as resting ventilation but do not affect delta VI/delta PACO2.
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PMID:Effects of upper or lower airway anesthesia on hypercapnic ventilation in humans. 405 88

Trigeminally innervated, mechanically sensitive chemoreceptors (M) were previously identified in rainbow trout, Oncorhynchus mykiss, but it is not known whether these receptors are responsive only to noxious, chemical irritants or have a general chemosensory function. This study aimed to characterise the stimulus-response properties of these receptors in comparison with polymodal nociceptors (P). Both P and M gave similar response profiles to acetic acid concentrations. The electrophysiological properties were similar between the two different afferent types. To determine whether the receptors have a nociceptive function, a range of chemical stimulants was applied to these receptors, including non-noxious stimuli such as ammonium chloride, bile, sodium bicarbonate and alarm pheromone, and potentially noxious chemical irritants such as acetic acid, carbon dioxide, low pH, citric acid, citric acid phosphate buffer and sodium chloride. Only irritant stimuli evoked a response, confirming their nociceptive function. All receptor afferents tested responded to carbon dioxide (CO(2)) in the form of mineral water or soda water. The majority responded to 1% acetic acid, 2% citric acid, citric acid phosphate buffer (pH 3) and 5.0 mol l(-1) NaCl. CO(2) receptors have been characterised in the orobranchial cavity and gill arches in fish; however, this is the first time that external CO(2) receptors have been identified on the head of a fish. Because the fish skin is in constant contact with the aqueous environment, contaminants with a low pH or hypercapnia may stimulate the nociceptive system in fish.
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PMID:Characterisation of chemosensory trigeminal receptors in the rainbow trout, Oncorhynchus mykiss: responses to chemical irritants and carbon dioxide. 2227 76