Effects of PACAP-38 on the SA nodal pacemaker activity in autonomically decentralized hearts of anesthetized dogs
Effects of PACAP-38 on the SA nodal pacemaker activity in autonomically decentralized hearts of anesthetized dogs
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DOI：
10.1097/00005344-199702000-00010
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发表时间：
1997-02-01
影响因子：
3
通讯作者：
Chiba, S
中科院分区：
文献类型：
--
作者：
Hirose, M;Furukawa, Y;Chiba, S
腺苷酸环化酶激活多肽（PACAP）受体存在，但PACAP的生理作用是不清楚的心脏原位。我们研究了PACAP-38对窦性心率和对乙酰胆碱（ACh）的负性变时性反应或对开胸麻醉犬的心脏分散性心脏中的心内副交感神经纤维对窦房结区域的刺激的影响。将PACAP-38（0.1-1 nmol）直接注射到窦房结动脉引起短暂的正性变时反应，随后是负性变时反应。阿托品和河豚毒素预处理均抑制对PACAP-38的负性变时性反应。然而，六甲铵不能阻断对PACAP-38的阴性反应。PACAP-38（0.1 ~ 1 nmol）作用于ACh后，心房颤动发生率显著增加（P < 0.01）。另一方面，对心内副交感神经刺激的负性变时性反应没有改变。这些结果表明：（a）PACAP-38诱导负性变时性反应，并从心内节后副交感神经释放ACh;（B）PACAP-38降低犬心脏原位ACh诱导的房颤阈值。
Pituitary adenylate cyclase-activating polypeptide (PACAP) receptors exist, but the physiologic role of PACAP is unclear in the heart in situ. We investigated effects of PACAP-38 on sinus rate and on the negative chronotropic response to acetylcholine (ACh) or stimulation of the intracardiac parasympathetic nerve fibers to the sinoatrial nodal region in the autonomically decentralized heart of the open-chest, anesthetized dog. PACAP-38 (0.1-1 nmol) injected directly into the sinus node artery caused transient positive followed by negative chronotropic responses. Both pretreatment with atropine and tetrodotoxin inhibited the negative chronotropic responses to PACAP-38. However, hexamethonium did not block the negative responses to PACAP-38. After treatment with PACAP-38 (0.1-1 nmol), ACh induced atrial fibrillation significantly (p < 0.01). On the other hand, the negative chronotropic responses to intracardiac parasympathetic stimulation were not changed. These results suggest that (a) PACAP-38 induces negative chronotropic responses and liberates ACh from intracardiac postganglionic parasympathetic nerves, and that (b) PACAP-38 reduces ACh-induced atrial fibrillation threshold in the dog heart in situ.