Calcitonin gene-related peptide activates different signaling pathways in mesenteric lymphatics of guinea pigs
Calcitonin gene-related peptide activates different signaling pathways in mesenteric lymphatics of guinea pigs
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DOI：
10.1152/ajpheart.00543.2005
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发表时间：
2006-02-01
影响因子：
4.8
通讯作者：
van Helden, DF
中科院分区：
文献类型：
--
作者：
Hosaka, K;Rayner, SE;van Helden, DF
本文观察了降钙素基因相关肽（CGRP）对离体豚鼠肠系膜血管收缩频率、平滑肌膜电位（V-m）和内皮细胞V-m的影响。CGRP（1 - 100 nM）引起灌注淋巴管收缩频率的内皮依赖性降低。内皮依赖性CGRP反应被CGRP-1受体拮抗剂CGRP-（8 - 37）（1 μ M）和百日咳毒素（100 ng/ml）消除。CGRP的这种作用也被一氧化氮（NO）合酶抑制剂N-G-硝基-（L）-精氨酸（（L）-NNA; 10 μ M）阻断，这种作用被加入（L）-精氨酸（100 μ M）逆转。cGMP、腺苷酸环化酶、cAMP依赖性蛋白激酶（PKA）和ATP敏感性K+（K-ATP（+））通道都与内皮依赖性CGRP反应有关，因为它被亚甲蓝（20 μ M）、1H-[1，2，4]恶二唑并[4，3a]喹喔啉-1-酮（10 μ M）、双脱氧腺苷（10 μ M）、N-[2-（对-溴肉桂酰氨基）乙基]-5-异喹啉磺酰胺-二氯化物（H89; 1 μ M）和格列本脲（10 μ M）。CGRP（100 nM），不像乙酰胆碱，不改变内皮细胞内Ca 2+浓度或Vm。CGRP（100 nM）使平滑肌Vm超极化，这种作用可被（L）-NNA、H89或格列本脲抑制。CGRP（500 nM）也引起收缩频率降低。然而，这不再被CGRP-（8 - 37）阻断。CGRP（500 nM）也引起平滑肌超极化，这一作用现在不被L-NNA（100 μ M）阻断。这很可能是通过激活cAMP/PKA通路和开放K-ATP（+）通道介导的，因为它被H89或格列本脲消除。我们得出结论，CGRP，在低到中等浓度（即，1-100 nM），主要通过刺激与百日咳毒素敏感性G蛋白偶联的CGRP- 1受体以及从内皮释放NO或增强内源性NO的作用来降低淋巴收缩频率。在高浓度下（即，500 nM），CGRP也直接激活不依赖于NO的平滑肌。这两种激活机制最终导致PKA介导的K-ATP（+）通道开放和由此产生的超极化。
The effects of calcitonin gene-related peptide ( CGRP) on constriction frequency, smooth muscle membrane potential (V-m), and endothelial Vm of guinea pig mesenteric lymphatics were examined in vitro. CGRP (1 - 100 nM) caused an endothelium-dependent decrease in the constriction frequency of perfused lymphatic vessels. The endothelium-dependent CGRP response was abolished by the CGRP-1 receptor antagonist CGRP-(8 - 37) (1 mu M) and pertussis toxin (100 ng/ml). This action of CGRP was also blocked by the nitric oxide (NO) synthase inhibitor N-G-nitro-(L)-arginine ((L)-NNA; 10 mu M), an action that was reversed by the addition of (L)-arginine (100 mu M). cGMP, adenylate cyclase, cAMP-dependent protein kinase (PKA), and ATP-sensitive K+ ( K-ATP(+)) channels were all implicated in the endothelium-dependent CGRP response because it was abolished by methylene blue (20 mu M), 1H-[1,2,4] oxadiazolo[4,3a] quinoxalin-1-one (10 mu M), dideoxyadenosine (10 mu M), N-[2-(p-bromociannamylamino)ethyl]- 5-isoquinolinesulfonamide-dichloride (H89; 1 mu M) and glibenclamide (10 mu M). CGRP (100 nM), unlike acetylcholine, did not alter endothelial intracellular Ca2+ concentration or Vm. CGRP ( 100 nM) hyperpolarized the smooth muscle Vm, an effect inhibited by (L)-NNA, H89, or glibenclamide. CGRP (500 nM) also caused a decrease in constriction frequency. However, this was no longer blocked by CGRP-( 8 - 37). CGRP ( 500 nM) also caused smooth muscle hyperpolarization, an action that was now not blocked by L-NNA (100 mu M). It was most likely mediated by the activation of the cAMP/PKA pathway and the opening of K-ATP(+) channels because it was abolished by H89 or glibenclamide. We conclude that CGRP, at low to moderate concentrations (i.e., 1-100 nM), decreases lymphatic constriction frequency primarily by the stimulation of CGRP- 1 receptors coupled to pertussis toxin-sensitive G proteins and the release of NO from the endothelium or enhancement of the actions of endogenous NO. At high concentrations (i.e., 500 nM), CGRP also directly activates the smooth muscle independent of NO. Both mechanisms of activation ultimately cause the PKA-mediated opening of K-ATP(+) channels and resultant hyperpolarization.