Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0231835 (tachypnea)
 2,543 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have assessed the functional role of type 2 purinergic (P2) receptors within the caudal aspect of the commissural nucleus tractus solitarii (NTS) in mediating the peripheral chemoreceptor reflex cardiorespiratory response in the arterially perfused in situ working heart-brainstem preparation of rats. Microinjection in NTS of either suramin (100 pmol) or pyrinoxalphosphate-6-azophenyl-2',4'-disulphonic acid tetrasodium salt (PPADS; 10 pmol) depressed the reflex bradycardia (by approximately 50 %), but not the tachypnoea, following peripheral chemoreceptor stimulation. In contrast, the reflex bradycardia produced by stimulation of pharyngo-oesophageal receptors was unaffected. Furthermore, microinjections in NTS of the P2X receptor agonist alpha,beta-methyleneadenosine 5'-triphosphate (10 pmol) evoked a bradycardia which was antagonized by suramin (100 pmol). This P2X agonist reversibly potentiated the peripheral chemoreceptor-evoked bradycardia. The effect of suramin was selective to purinergic receptors because the bradycardia evoked by microinjection of alpha,beta-methyleneadenosine 5'-triphosphate was blocked while the bradycardic responses to microinjections of NMDA or non-NMDA receptor agonists were not affected. From whole-cell recordings, some NTS neurones received convergent excitatory synaptic inputs from both peripheral chemoreceptors and receptors at the pharyngo-oesophageal junction. The excitatory postsynaptic response evoked by chemoreceptor stimulation was depressed by suramin, but convergent excitatory inputs from pharyngo-oesophageal receptors were unperturbed. Our findings support the hypothesis that caudal commissural NTS P2 purinergic receptors play a role in the neurotransmission of the parasympathetic (bradycardic) component of the chemoreceptor reflex. This effect is highly selective in that the chemoreceptor afferent-evoked tachypnoea, as well as other visceral receptor-mediated reflex bradycardia, remain unaffected.
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PMID:Sensory afferent selective role of P2 receptors in the nucleus tractus solitarii for mediating the cardiac component of the peripheral chemoreceptor reflex in rats. 1223 53

Inhalation of H2O2 is known to evoke bradypnea followed by tachypnea, which are reflexes resulting from stimulation by reactive oxygen species of vagal lung capsaicin-sensitive and myelinated afferents, respectively. This study investigated the pharmacological receptors and chemical mediators involved in triggering these responses. The ventilatory responses to 0.2% aerosolized H2O2 were studied before and after various pharmacological pretreatments in anesthetized rats. The initial bradypneic response was reduced by a transient receptor potential vanilloid 1 (TRPV1) receptor antagonist [capsazepine; change (Delta) = -53%] or a P2X purinoceptor antagonist [iso-pyridoxalphosphate-6-azophenyl-2',5'-disulphonate (PPADS); Delta = -47%] and was further reduced by capsazepine and iso-PPADS in combination (Delta = -78%). The initial bradypneic response was reduced by a cyclooxygenase inhibitor (indomethacin; Delta = -48%), ATP scavengers (apyrase and adenosine deaminase in combination; Delta = -50%), or capsazepine and indomethacin in combination (Delta = -47%), was further reduced by iso-PPADS and indomethacin in combination (Delta = -75%) or capsazepine and ATP scavengers in combination (Delta = -83%), but was not affected by a lipoxygenase inhibitor (nordihydroguaiaretic acid) or by any of the various vehicles. No pretreatment influenced delayed tachypnea. We concluded that 1) the initial bradypneic response to H2O2 results from activation of both TRPV1 and P2X receptors, possibly located at terminals of vagal lung capsaicin-sensitive afferent fibers; 2) the functioning of the TRPV1 and P2X receptors in triggering the initial bradypnea is, in part, mediated through the actions of cyclooxygenase metabolites and ATP, respectively; and 3) these mechanisms do not contribute to the H2O2-evoked delayed tachypnea.
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PMID:Mediator mechanisms involved in TRPV1 and P2X receptor-mediated, ROS-evoked bradypneic reflex in anesthetized rats. 1662 82