Cardio-respiratory reflexes evoked by phenylbiguanide in rats involve vagal afferents which are not sensitive to capsaicin
Cardio-respiratory reflexes evoked by phenylbiguanide in rats involve vagal afferents which are not sensitive to capsaicin
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DOI：
10.1111/j.1748-1716.2010.02105.x
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发表时间：
2010-09-01
影响因子：
6.3
通讯作者：
Deshpande, S. B.
中科院分区：
文献类型：
--
作者：
Dutta, A.;Deshpande, S. B.
目的：苯双胍（PBG，5-HT（3）激动剂）刺激肺C纤维受体可引起低血压、心动过缓和呼吸急促或呼吸暂停。然而，呼吸急促或呼吸暂停反应并不一致。因此，本研究进行了描述PBG对呼吸的作用，并与辣椒素（TRPV 1激动剂）诱发的呼吸进行了比较。方法：在乌拉坦麻醉的成年大鼠记录血压，呼吸偏移和心电图。观察5-HT（3）受体拮抗剂昂丹司琼（ondansetron）、TRPV 1受体拮抗剂辣椒平（capsazepine）或双侧迷走神经切断术前后PBG或辣椒素的作用。此外，他们对迷走神经传入活动的影响也evaluated.Results：团注PBG产生浓度依赖性（0.1-100 μ g kg-1）膨胀和心动过缓的反应，而有呼吸急促在较低浓度（0.1-3 μ g kg-1）和呼吸暂停在较高浓度（10-100 μ g kg-1）。迷走神经切断后或暴露于昂丹司琼后，呼吸急促和呼吸暂停反应都被消除沿着心血管反应。然而，辣椒平（3毫克kg-1）并没有阻止PBG诱导的反射反应。另一方面，辣椒素（0.1-10 μ g kg-1）会产生浓度依赖性呼吸暂停、低血压和心动过缓，但未观察到呼吸急促。昂丹司琼不能阻断辣椒素引起的反射反应，而双侧迷走神经切断则能消除心动过缓和呼吸暂停反应，并能减弱呼吸暂停反应。在另一个系列中，迷走神经传入活动和心肺功能的变化引起的PBG阻断昂丹司琼。然而，辣椒素未能激活PBG敏感的迷走神经传入，即使心脏呼吸alterations observed.Conclusions：目前的观察表明，PBG产生呼吸急促在较低的浓度和呼吸暂停在较高的浓度涉及迷走神经传入，这是不同的兴奋辣椒素。
Aim:Stimulation of pulmonary C fibre receptors by phenylbiguanide (PBG, 5-HT(3) agonist) produces hypotension, bradycardia and tachypnoea or apnoea. However, tachypnoeic or apnoeic responses are not consistent. Therefore, this study was undertaken to delineate the actions of PBG on respiration and compared with those evoked by capsaicin (TRPV1 agonist).Methods:Blood pressure, respiratory excursions and ECG were recorded in urethane anaesthetized adult rats. The effect of PBG or capsaicin was evaluated before and after ondansetron (5-HT(3) antagonist), capsazepine (TRPV1 antagonist) or bilateral vagotomy. In addition, their effect on vagal afferent activity was also evaluated.Results:Bolus injection of PBG produced concentration-dependent (0.1-100 mu g kg-1) hypotensive and bradycardiac responses, while there was tachypnoea at lower concentrations (0.1-3 mu g kg-1) and apnoea at higher concentrations (10-100 mu g kg-1). After vagotomy or after exposure to ondansetron both tachypnoeic and apnoeic responses were abolished along with cardiovascular responses. However, capsazepine (3 mg kg-1) did not block the PBG-induced reflex responses. Capsaicin (0.1-10 mu g kg-1), on the other hand, produced a concentration-dependent apnoea, hypotension and bradycardia but tachypnoea was not observed. Ondansetron failed to block the capsaicin-induced reflex response while bilateral vagotomy abolished bradycardiac and hypotensive responses and attenuated the apnoeic response. In another series, vagal afferent activity and cardio-respiratory changes evoked by PBG were blocked by ondansetron. However, capsaicin failed to activate the PBG-sensitive vagal afferents even though cardio-respiratory alterations were observed.Conclusions:The present observations indicate that PBG produced tachypnoea at a lower concentration and apnoea at a higher concentration involving vagal afferents which are different from those excited by capsaicin.