Barrera Nelson P, Márquez Mónica, Muñoz-Uribe Matías, Figueroa Xavier F
Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
Front Physiol. 2025 May 30;16:1569167. doi: 10.3389/fphys.2025.1569167. eCollection 2025.
INTRODUCTION: The conduction of changes in the diameter of arterioles plays an important role in the coordination of the blood flow distribution. The endothelium regulates vasomotor tone by generation of vasodilator signals, such as nitric oxide (NO) and endothelium-derived hyperpolarization (EDH). Endothelium-mediated vasodilator responses initiated in an arteriolar segment are conducted along the vessel length, which depends on the electrotonic spread of EDH signaling activated at the stimulation site, but, in contrast, the contribution of NO is controversial. METHODS: We used the mouse cremaster muscle microcirculation to analyze the participation of NO in the mechanisms involved in the conducted vasodilation observed in response to the stimulation of a short arteriolar segment with a pulse of acetylcholine (ACh), an endothelium-dependent vasodilator, or S-nitroso-N-acetylpenicillamine (SNAP), an NO donor. RESULTS: The response to ACh spread along the entire vessel showing only a slight decay and, in contrast, the dilation evoked by SNAP was restricted to the stimulation site, independently of the magnitude of the response. Blockade of NO production with 100 μM N-nitro-L-arginine methyl ester (LNAME) or 100 µM N-nitro-L-arginine (L-NA) reduced the arteriolar resting diameter by 10%-12%, but the combined application of both blockers enhanced the basal vasoconstrictor tone by ∼38% and inhibited the local (∼45%) and conducted (∼20%-35%) responses initiated by ACh. Interestingly, the conduction of ACh-induced vasodilation increased along the vessel length in the presence of L-NAME and L-NA. In addition, blockade of endothelial cell hyperpolarization exclusively at the stimulation site through microsuperfusion of tetraethylammonium (TEA) inhibited the local vasodilation, but not the conduction of the response. CONCLUSION: These results suggest that ACh activates an NO sensitive mechanism of regenerative propagation of vasodilator responses, which contributes to our understanding of microvascular function and the complex integration of endothelial signaling pathways in the coordination of the blood flow distribution.
引言:小动脉直径变化的传导在血流分布的协调中起着重要作用。内皮细胞通过产生血管舒张信号来调节血管舒缩张力,如一氧化氮(NO)和内皮源性超极化(EDH)。在小动脉节段起始的内皮介导的血管舒张反应会沿着血管长度进行传导,这取决于在刺激部位激活的EDH信号的电紧张性扩布,然而,相比之下,NO的作用存在争议。 方法:我们使用小鼠提睾肌微循环来分析NO在对短节段小动脉进行乙酰胆碱(ACh,一种内皮依赖性血管舒张剂)脉冲刺激或S-亚硝基-N-乙酰青霉胺(SNAP,一种NO供体)刺激所观察到的传导性血管舒张机制中的参与情况。 结果:对ACh的反应沿整个血管进行传播,仅显示出轻微衰减,相反,SNAP引起的扩张局限于刺激部位,与反应幅度无关。用100μM N-硝基-L-精氨酸甲酯(LNAME)或100μM N-硝基-L-精氨酸(L-NA)阻断NO生成可使小动脉静息直径降低10%-12%,但两种阻断剂联合应用可使基础血管收缩张力增强约38%,并抑制ACh引发的局部(约45%)和传导性(约20%-35%)反应。有趣的是,在存在L-NAME和L-NA的情况下,ACh诱导的血管舒张传导沿血管长度增加。此外,通过四乙铵(TEA)微灌注仅在刺激部位阻断内皮细胞超极化可抑制局部血管舒张,但不抑制反应的传导。 结论:这些结果表明,ACh激活了一种对NO敏感的血管舒张反应再生传播机制,这有助于我们理解微血管功能以及内皮信号通路在血流分布协调中的复杂整合。
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