The peptide hormone pQDLDHVFLRFamide (crustacean myosuppressin) modulates the Homarus americanus cardiac neuromuscular system at multiple sites
The peptide hormone pQDLDHVFLRFamide (crustacean myosuppressin) modulates the Homarus americanus cardiac neuromuscular system at multiple sites
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DOI：
10.1242/jeb.035741
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发表时间：
2009-12-15
影响因子：
2.8
通讯作者：
Dickinson, P. S.
中科院分区：
文献类型：
--
作者：
Stevens, J. S.;Cashman, C. R.;Dickinson, P. S.
pQDLDHVFLRF酰胺是一种高度保守的甲壳动物神经肽，其结构将其置于FMRFamide样肽的肌抑制素亚家族内。尽管其在十足类甲壳动物中明显普遍存在，但pQDLDHVFLRFamide所起的旁分泌和/或内分泌作用在很大程度上仍然未知。我们已经研究了这种肽的行动对心脏神经肌肉系统的美国龙虾Homarus americanus使用四个准备：完整的动物，心脏在体外，分离的心脏神经节（CG），和刺激的心肌制备。在完整的动物中，注射肌抑制素导致心跳频率降低。用pQDLDHVFLRF酰胺灌注体外心脏引起心脏收缩频率降低和幅度增加。在隔离的CG，myosuppressin诱导心肌运动神经元的静息膜电位的超极化和减少其爆裂的周期频率。在刺激的心肌制备中，pQDLDHVFLRFamide增加了诱导收缩的幅度，表明肌抑制素不仅调节CG，而且调节外周部位。至少对于体外心脏和分离的CG，肌抑制素的作用是剂量依赖性的（10（-9）至10（-6））。摩尔l（-1）测试），阈值浓度（10（-8）-10（-7））。摩尔l（-1）），这与用作循环激素的肽一致。虽然周期频率，一个参数直接确定的CG，一致下降时，pQDLDHVFLRF酰胺适用于所有的准备类型，这种减少的幅度不同，这表明的可能性，因为肌抑制素调节CG和周边，它也改变周边反馈的CG。
pQDLDHVFLRFamide is a highly conserved crustacean neuropeptide with a structure that places it within the myosuppressin subfamily of the FMRFamide-like peptides. Despite its apparent ubiquitous conservation in decapod crustaceans, the paracrine and/or endocrine roles played by pQDLDHVFLRFamide remain largely unknown. We have examined the actions of this peptide on the cardiac neuromuscular system of the American lobster Homarus americanus using four preparations: the intact animal, the heart in vitro, the isolated cardiac ganglion (CG), and a stimulated heart muscle preparation. In the intact animal, injection of myosuppressin caused a decrease in heartbeat frequency. Perfusion of the in vitro heart with pQDLDHVFLRFamide elicited a decrease in the frequency and an increase in the amplitude of heart contractions. In the isolated CG, myosuppressin induced a hyperpolarization of the resting membrane potential of cardiac motor neurons and a decrease in the cycle frequency of their bursting. In the stimulated heart muscle preparation, pQDLDHVFLRFamide increased the amplitude of the induced contractions, suggesting that myosuppressin modulates not only the CG, but also peripheral sites. For at least the in vitro heart and the isolated CG, the effects of myosuppressin were dose-dependent (10(-9) to 10(-6). mol. l(-1) tested), with threshold concentrations (10(-8)-10(-7). mol. l(-1)) consistent with the peptide serving as a circulating hormone. Although cycle frequency, a parameter directly determined by the CG, consistently decreased when pQDLDHVFLRFamide was applied to all preparation types, the magnitudes of this decrease differed, suggesting the possibility that, because myosuppressin modulates the CG and the periphery, it also alters peripheral feedback to the CG.