Ren L M, Furukawa Y, Karasawa Y, Murakami M, Takei M, Narita M, Chiba S
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
J Pharmacol Exp Ther. 1991 Oct;259(1):38-43.
Neuropeptide Y (NPY) inhibits the release of noradrenaline (NA) or acetylcholine (ACh) from nerve terminals in the heart. Thus, we differentiated the blocking effects of NPY on the negative and positive (atrial chronotropic and inotropic) responses to simultaneous stimulation of the intracardiac parasympathetic and sympathetic nerves in isolated, blood-perfused dog atria. NPY (0.1-3 nmol) injected into the sinus node artery decreased atrial contractile force slightly, but not sinus rate by itself. NPY inhibited the negative atrial responses to intracardiac autonomic nerve stimulation in a dose-dependent manner, whereas it rather augmented the positive responses. The inhibition on the negative chronotropic effect was more prolonged than that on the inotropic one. NPY also inhibited the negative responses to intracardiac parasympathetic nerve stimulation alone. However, NPY (3 nmol) did not change the positive responses to intracardiac sympathetic stimulation after atropine was given. NPY did not affect the atrial responses to exogenous ACh or NA. These results suggest that, under activation of autonomic nerves, NPY released from sympathetic nerves attenuates the negative chronotropic and inotropic responses to ACh released from parasympathetic nerves at the prejunctional sites more effectively than the positive responses to NA released from sympathetic nerves, and modifies the sympathetic-parasympathetic interactions in the dog heart.
神经肽Y（NPY）抑制心脏神经末梢去甲肾上腺素（NA）或乙酰胆碱（ACh）的释放。因此，我们区分了NPY对离体血液灌注犬心房中心内副交感神经和交感神经同时刺激的负性和正性（心房变时性和变力性）反应的阻断作用。注入窦房结动脉的NPY（0.1 - 3 nmol）自身对心房收缩力有轻微降低，但对窦性心率无影响。NPY以剂量依赖方式抑制心脏自主神经刺激引起的心房负性反应，而对正性反应则有增强作用。对负性变时性效应的抑制比对变力性效应的抑制持续时间更长。NPY也单独抑制心脏副交感神经刺激引起的负性反应。然而，给予阿托品后，NPY（3 nmol）并未改变心脏交感神经刺激引起的正性反应。NPY不影响心房对外源性ACh或NA的反应。这些结果表明，在自主神经激活的情况下，交感神经释放的NPY在神经节前部位比交感神经释放的NA引起的正性反应更有效地减弱了副交感神经释放的ACh引起的负性变时性和变力性反应，并改变了犬心脏中的交感 - 副交感相互作用。
