{"title":"大鼠肺迷走神经传入末梢对化学刺激物的敏感性","authors":"C.-Y Ho , Q Gu , Y.S Lin , L.-Y Lee","doi":"10.1016/S0034-5687(01)00241-9","DOIUrl":null,"url":null,"abstract":"<div><p>This study was carried out to investigate the relationship between the conduction velocity of the vagal afferents arising from the rat lungs and their sensitivities to capsaicin, other chemical irritants, and lung inflation. We recorded single-unit activities of vagal pulmonary afferents (<em>n</em>=205) in anesthetized, open-chest rats, and distinguished C fibers (conduction velocity<2 m/sec) from myelinated afferents; the latter group was further classified into rapidly adapting pulmonary receptors (RARs) and slowly adapting pulmonary stretch receptors (SARs) on the basis of their adaptation indexes to lung inflation. Right-atrial injection of capsaicin (1 μg/kg) evoked an abrupt and intense stimulatory effect in 88.9% (64/72) of the pulmonary C fibers tested, but only a mild stimulation in 6.3% (3/48) of the RARs and none of the SARs. Other inhaled and injected chemical stimulants (e.g., cigarette smoke, lactic acid) activated 68.9% (42/61) of the pulmonary C fibers. The same chemical irritants exerted a mild stimulatory effect in only 14.5% (8/55) of the RARs; this subgroup of RARs exhibited a low or no baseline activity, and half of them were located near the hilum. Chemical stimulants had little or no effect on SARs. The response of pulmonary C fibers to lung inflation (tracheal pressure=30 cm H<sub>2</sub>O) was not only extremely weak, but also showed a longer onset latency and an irregular pattern. In a sharp contrast, lung inflation evoked rapid and vigorous discharges in both RARs and SARs. In conclusion, C fibers are the primary type of chemosensitive vagal pulmonary afferents in rat lungs.</p></div>","PeriodicalId":20976,"journal":{"name":"Respiration physiology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2001-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0034-5687(01)00241-9","citationCount":"207","resultStr":"{\"title\":\"Sensitivity of vagal afferent endings to chemical irritants in the rat lung\",\"authors\":\"C.-Y Ho , Q Gu , Y.S Lin , L.-Y Lee\",\"doi\":\"10.1016/S0034-5687(01)00241-9\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>This study was carried out to investigate the relationship between the conduction velocity of the vagal afferents arising from the rat lungs and their sensitivities to capsaicin, other chemical irritants, and lung inflation. We recorded single-unit activities of vagal pulmonary afferents (<em>n</em>=205) in anesthetized, open-chest rats, and distinguished C fibers (conduction velocity<2 m/sec) from myelinated afferents; the latter group was further classified into rapidly adapting pulmonary receptors (RARs) and slowly adapting pulmonary stretch receptors (SARs) on the basis of their adaptation indexes to lung inflation. Right-atrial injection of capsaicin (1 μg/kg) evoked an abrupt and intense stimulatory effect in 88.9% (64/72) of the pulmonary C fibers tested, but only a mild stimulation in 6.3% (3/48) of the RARs and none of the SARs. Other inhaled and injected chemical stimulants (e.g., cigarette smoke, lactic acid) activated 68.9% (42/61) of the pulmonary C fibers. The same chemical irritants exerted a mild stimulatory effect in only 14.5% (8/55) of the RARs; this subgroup of RARs exhibited a low or no baseline activity, and half of them were located near the hilum. Chemical stimulants had little or no effect on SARs. The response of pulmonary C fibers to lung inflation (tracheal pressure=30 cm H<sub>2</sub>O) was not only extremely weak, but also showed a longer onset latency and an irregular pattern. In a sharp contrast, lung inflation evoked rapid and vigorous discharges in both RARs and SARs. In conclusion, C fibers are the primary type of chemosensitive vagal pulmonary afferents in rat lungs.</p></div>\",\"PeriodicalId\":20976,\"journal\":{\"name\":\"Respiration physiology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2001-09-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/S0034-5687(01)00241-9\",\"citationCount\":\"207\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Respiration physiology\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0034568701002419\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Respiration physiology","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0034568701002419","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 207
摘要
本研究旨在探讨由大鼠肺产生的迷走神经传入神经的传导速度与其对辣椒素、其他化学刺激物和肺膨胀的敏感性之间的关系。我们记录了麻醉、开胸大鼠迷走神经肺传入神经(n=205)的单单位活动,并从髓鞘传入神经中区分出C纤维(传导速度为2m /秒);根据对肺膨胀的适应指数,将后者进一步分为快速适应肺受体(RARs)和慢适应肺伸展受体(SARs)。右心房注射辣椒素(1 μg/kg)对88.9%(64/72)的肺C纤维有突然的强烈刺激作用,但对6.3%(3/48)的rar有轻微刺激作用,对SARs无刺激作用。其他吸入和注射的化学刺激物(如香烟烟雾、乳酸)激活68.9%(42/61)的肺C纤维。相同的化学刺激物仅对14.5%(8/55)的RARs产生轻度刺激作用;该亚组RARs表现出较低或无基线活性,其中一半位于门附近。化学兴奋剂对SARs的作用很小或没有作用。肺C纤维对肺充气(气管压=30 cm H2O)的反应极弱,且起病潜伏期较长,形态不规则。与之形成鲜明对比的是,肺膨胀在RARs和SARs中都引起了快速和剧烈的放电。综上所述,C纤维是大鼠肺化学敏感迷走神经传入神经的主要类型。
Sensitivity of vagal afferent endings to chemical irritants in the rat lung
This study was carried out to investigate the relationship between the conduction velocity of the vagal afferents arising from the rat lungs and their sensitivities to capsaicin, other chemical irritants, and lung inflation. We recorded single-unit activities of vagal pulmonary afferents (n=205) in anesthetized, open-chest rats, and distinguished C fibers (conduction velocity<2 m/sec) from myelinated afferents; the latter group was further classified into rapidly adapting pulmonary receptors (RARs) and slowly adapting pulmonary stretch receptors (SARs) on the basis of their adaptation indexes to lung inflation. Right-atrial injection of capsaicin (1 μg/kg) evoked an abrupt and intense stimulatory effect in 88.9% (64/72) of the pulmonary C fibers tested, but only a mild stimulation in 6.3% (3/48) of the RARs and none of the SARs. Other inhaled and injected chemical stimulants (e.g., cigarette smoke, lactic acid) activated 68.9% (42/61) of the pulmonary C fibers. The same chemical irritants exerted a mild stimulatory effect in only 14.5% (8/55) of the RARs; this subgroup of RARs exhibited a low or no baseline activity, and half of them were located near the hilum. Chemical stimulants had little or no effect on SARs. The response of pulmonary C fibers to lung inflation (tracheal pressure=30 cm H2O) was not only extremely weak, but also showed a longer onset latency and an irregular pattern. In a sharp contrast, lung inflation evoked rapid and vigorous discharges in both RARs and SARs. In conclusion, C fibers are the primary type of chemosensitive vagal pulmonary afferents in rat lungs.