Objective Chronic cough is often present as increasing cough reaction to various physical and chemical stimulating factors. This study is aimed to investigate the difference of cough sensitivity and its mechanisms which are not clear among different causes of chronic cough. Methods Patients with chronic cough were recruited from cough clinic of Guangzhou Institute of Respiratory Diseases between 2005 to 2010. Using a modified diagnostic algorithm of chronic cough, common causes were identified. Capsaicin cough provocation test was also performed in these patients to assess the cough threshold. The relations between cough reflex sensitivity and duration of cough, cough severity, pulmonary function, induced sputum cell counts were then investigated. Results Through the diagnostic algorithm of chronic cough, the current study evaluated 133 adult patients, including 24 cases with upper airway cough syndrome (UACS) , 26 patients with cough variant asthma (CVA) , 31 cases with eosinophilic bronchitis (EB) , 30 patients with atopic cough (AC) , 22 cases with gastroesophageal reflux induced cough (GERC) . There were 30 healthy volunteers recruited as normal control. The cough threshold of LgC5 in AC, CVA, EB, GERC and UACS was 1.70 ±0.70, 2.12 ±0.67, 2.13 ±0.69, 1.69 ±0.73, 2.16 ±0.66, respectively. The LgC5 of the normal group ( 2.63 ±0.39) was higher than those in chronic cough groups( All P lt; 0.05) . The LgC5 of AC and GERC were lower than CVA, EB and UACS ( all Plt;0.05) . Duration and daytime score of cough showed positive correlations with LgC5( r =-0. 280, -0. 168, all P lt;0.05) . Pulmonary function and differential cell count of induced sputumwere not associated with LgC5 ( all Pgt;0.05) . Conclusions Different cause of chronic cough exhbit high cough reflex sensitivity to different extent. The difference of cough sensitivity may reflect the different pathogenesis among different causes, and may be related to the type of nerve fiber dominating the cough reflex.
The purpose of this study is to discuss the feasibility of establishing capsaicin pain model and the possibility to evaluate different degrees of pain by the heart rate variability (HRV). It also aims to investigate the changes of autonomic nervous activity of volunteers during the process of pain caused by capsaicin. A total of 30 volunteers were selected, who were physically and mentally healthy, into the study. To assess the effects of capsaicin on the healthy volunteers, we recorded the Visual Analogue Scale (VAS) scores after the capsaicin stimulus. Additionally, the electrocardiogram signals and HRV analysis index before and after stimulating were also recorded, respectively. More specifically, the HRV analysis indexes included the time domain index, the frequency domain index, and the nonlinear analysis index. The results demonstrated that the activity of the autonomic nerves was enhanced in the process of capsaicin stimulus, especially for the sympathetic nerve, which exhibited a significantly differences in HRV. In conclusion, the degree of pain can be reflected by the HRV. It is feasible to establish a capsaicin pain model. And in further experiments, HRV analysis could be used as a reference index for quantitative evaluation of pain.
【摘要】 目的 探討辣椒素對不同年齡SD大鼠內臟感覺神經元上辣椒素受體（TRPV1）介導的離子通道的影響。 方法 急性分離7~9 d和21~23 d大鼠迷走神經結狀神經節神經元，利用全細胞膜片鉗技術在分離的神經元上記錄辣椒素激活TRPV1受體后通道電流的變化。 結果 ①7~9 d和21~23 d大鼠內臟感覺神經元的膜電容分別為（18.57±8.60）和（19.85±9.47） pF，（Pgt;0.05）；②辣椒素能夠激活7~9 d和21~23 d大鼠內臟感覺神經元上TRPV1并產生相似的內向電流，兩組產生的峰電流密度分別為（48.59±18.87）、（55.91±20.52） pA/pF（Pgt;0.05）；③反復應用辣椒素使TRPV1受體發生失敏現象。 結論 大鼠內臟感覺神經元的TRPV1受體通道在出生后已經發育成熟，且對辣椒素激活的通道電流有相似的變化。【Abstract】 Objective To investigate the effects of capsaicin on transient receptor potential vanilloid 1 (TRPV1) receptor-mediated ion channel currents of visceral sensory neurons in different-aged Sprague-Dawley rats. Methods We isolated the vagal nodose ganglion neurons of rats at an age of 7-9 days or 21-23 days acutely. With the whole cell patch clamp technique, we recorded the current changes of TRPV1 channels activated by capsaicin. Results ① Membrane capacitances of the visceral sensory neurons were (18.57±8.60) and (19.85±9.47) pF in rats of 7-9 and 21-23 days, respectively (Pgt;0.05). ② Capsaicin activated the TRPV1 channels and generated inward currents in all the rats; and the peak current densities of the rats of 7-9 days and 21-23 days were respectively (48.59±18.87) and (55.91±20.52) pA/pF (Pgt;0.05). ③ Repeated applications of capsaicin produced a phenomenon of desensitization in TRPV1 channels. Conclusion TRPV1 receptor channels of visceral sensory neurons in rats have matured after birth, and the current changes of TRPV1 channels activated by capsaicin are similar.
