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

Neonatal apnea is characterized by decreased neural output to the ventilatory muscles, and frequently associated with upper airway obstruction. We sought to characterize: (1) the role of central chemosensitive structures at the ventral medullary surface (VMS) in modulating hypoglossal and phrenic neural output, and (2) the recovery of hypoglossal and phrenic neural output during simulated central apnea. We studied 14 anesthetized, paralyzed, ventilated piglets aged 14-21 days and performed VMS cooling to inhibit central neural pathways mediating CO2 sensitivity. Phrenic and hypoglossal ENGs and end-tidal CO2 were continuously recorded. During CO2 rebreathing, hypoglossal activity was always more sensitive than phrenic activity to the inhibitory effects of VMS cooling. When phrenic apnea was induced by VMS cooling, and followed by discontinuation of ventilation for 60 sec in order to induce simultaneous hypercapnia and hypoxia, reappearance of hypoglossal ENG was delayed and recovery was significantly suppressed when compared to phrenic ENG. Therefore, attenuated central chemosensitivity during early postnatal life appears to preferentially inhibit neural output responsible for upper airway patency, and may predispose to upper airway obstruction during recovery from neonatal apnea.
 ...
PMID:Hypoglossal and phrenic responses to central respiratory inhibition in piglets. 809 Oct 27

In this study, the activities of the two external glossal muscles, Genioglossus (Gg) and Styloglossus (Sg), related to respiration were examined through the electromyography (EMG) in dog. During quiet breathing, no phasic respiratory activity were observed in either muscle. With hypercapnic condition induced by closed rebreathing respiratory system, both Sg and Gg showed phasic respiratory activities in respiration period. At first inspiratory EMG activity was observed from Sg (PaCO2 > 50 mmHg), then after a while from Gg (PaCO2 > 55 mmHg). NaCN injection bilaterally to the carotid body enhances the inspiratory ENG activities in both muscles. Sg was more sensitive than Gg to respiratory stimulation such as hypercapnia or NaCN injection.
 ...
PMID:Respiratory activities in relation to external glossal muscles. 893 79

The effects of recurrent hypoxia on cardiorespiratory reflexes were characterized in anesthetized piglets at 2-10 d (n=15), 2-3 weeks (n=11) and 8-10 weeks (n=8). Responses of phrenic and hypoglossal electroneurograms (ENG(phr) and ENG (hyp)) to hypoxia (8% 0(2), bal N(2), 5 min), hypercapnia (7% CO(2) bal O(2), 5 min) and intravenous capsaicin were tested before and after recurrent exposure to 11 episodes of hypoxia (8% O(2) bal N(2), 5 min). In piglets 2-10 d, ENG(phr) response to hypoxia declined in proportion to the number of hypoxic exposures; however, ENG (hyp) response to hypoxia was unchanged. In piglets at 2-10 d, intracisternal injection of bicuculline (GABA(A) receptor antagonist) reversed effects of recurrent hypoxia on ENG(phr) hypoxic response, eliminated apnea during hypoxia, as well as the delay in appearance of ENG(phr) after hypoxia. The ENG(phr) response to 7% CO(2) inhalation also decreased after recurrent hypoxia; however, the ENG(phr) response to C-fiber stimulation by capsaicin was unaltered. Piglets at 2-3 and 8-10 weeks were resistant to the depressive effects of recurrent hypoxia on respiratory reflex responses. We conclude that the response of the anesthetized newborn piglet to recurrent hypoxia is dominated by increasing inhibition of phrenic neuroelectrical output during successive hypoxic exposures. Central GABAergic inhibition may contribute significantly to the cumulative effects of repeated hypoxia in the newborn piglet experimental model.
 ...
PMID:Recurrent hypoxic exposure and reflex responses during development in the piglet. 1099 87