Acute hypoxia prolongs the apnea induced by right atrial injection of capsaicin.
Acute hypoxia prolongs the apnea induced by right atrial injection of capsaicin.
复制标题
急性缺氧可延长右心房注射辣椒素引起的呼吸暂停。
DOI：
10.1152/japplphysiol.00767.2002
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Lee,Lu-Yuan
中科院分区：
文献类型：
--
作者：
Xu,Fadi;Gu,Qi-Hai;Zhou,Tongrong;Lee,Lu-Yuan
Inspiratory central drive is augmented by acute hypoxia that leads to a hyperventilation, but it is inhibited by capsaicin (Cap)-induced stimulation of pulmonary C fibers (PCFs) that produces an expiratory apnea. We hypothesized that acute hypoxia should shorten or eliminate the Cap-induced apnea. The ventilatory responses to bolus injection of Cap (0.2–0.5 μg) into the right atrium before and during acute hypoxia (10% O2for ∼1 min; Hypoxia+Cap) were compared in anesthetized and spontaneously breathing rats. We found that Cap injection during acute hypoxia produced an extremely long-lasting apnea (69.67 ± 11.97 s) that was 16-fold longer than the apnea induced by Cap alone (expiratory duration = 4.37 ± 0.53 s;P< 0.01). A similar prolonged apnea was also observed during hypoxia in anesthetized guinea pigs. Bilateral vagotomy abolished apneic responses to Cap both before and during hypoxia. Subsequent recording of single-fiber activity of PCFs (PCFA) showed that acute hypoxia did not significantly affect baseline PCFAbut that it doubled PCFAresponses to Cap via increasing both the firing rate (3.34 ± 0.76 to 7.65 ± 1.32 impulses/s;P< 0.05) and burst duration (1.12 ± 0.18 to 2.32 ± 0.31 s;P< 0.05). These results suggest that acute hypoxia augments PCF-mediated inspiratory inhibition and thereby leads to an extremely long-lasting apnea. This interaction is partially due to hypoxic sensitization of PCF response to Cap.
