Cochlear blood flow regulation.
Cochlear blood flow regulation.
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DOI：
10.1159/000059241
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发表时间：
2002
影响因子：
--
通讯作者：
P. Wangemann
中科院分区：
文献类型：
--
作者：
P. Wangemann
由于耳蜗这种感觉器官对缺氧的敏感性，耳蜗血流的调节对听觉功能至关重要。耳蜗血流量的部分调节发生在为耳蜗提供主要血液供应的螺旋模侧动脉。一般来说，通过控制血管直径最有效地调节血流量。血管直径是由血管壁平滑肌细胞的收缩程度决定的。平滑肌细胞的收缩减小了血管腔的直径，从而减少了血流量，而平滑肌细胞的松弛则增加了血流量。螺旋型小臼齿动脉内平滑肌细胞的收缩程度应严格控制，并根据耳蜗组织的需要适当调整。为了达到适当的控制，平滑肌细胞整合来自不同来源的信息。血管收缩和扩张可能来源于血管周围的神经支配、血管腔内的内皮细胞或平滑肌细胞本身。最近的研究进展表明，来自不同小动脉的平滑肌细胞在其禀性上存在很大差异，其调节平滑肌细胞张力程度的机制也存在很大差异。信号转导机制，介导这些神经源性，局部和旁分泌调节平滑肌收缩现在开始被理解。本文综述了最近获得的肾上腺素能调节耳蜗血流的证据，并重点介绍了一种新的血管舒张机制，该机制涉及ryanodine受体、Ca2+火花和Ca2+激活的K+通道的激活。
The regulation of cochlear blood flow is crucial for auditory function due to the sensitivity of this sensory organ to hypoxia. Part of the regulation of cochlear blood flow occurs in the spiral modiolar artery, which provides the main blood supply to the cochlea. Blood flow in general is most effectively regulated through the control of the vascular diameter. The vascular diameter is determined by the degree of constriction of the smooth muscle cells in the vascular wall. A constriction of the smooth muscle cells reduces the diameter of the vascular lumen and thereby decreases blood flow, whereas a relaxation of the smooth muscle cells increases blood flow. The degree of constriction of the smooth muscle cells in the spiral modiolar artery is carefully controlled and must be adjusted properly to the demands of the cochlear tissues. To achieve proper control, smooth muscle cells integrate information from various sources. Vasoconstrictors and dilators may originate from the innervation surrounding the vessel, from endothelial cells lining the vascular lumen or from the smooth muscle cells themselves. Recent advances revealed that smooth muscle cells from different arterioles differ widely in their endowment with mechanisms that regulate the degree of smooth muscle cell tone. Signal transduction mechanisms, which mediate these neurogenic, local and paracrine regulations of smooth muscle contractility are now beginning to be understood. This report reviews recently obtained evidence for adrenergic regulation of cochlear blood flow and then focuses on a novel vasodilation mechanism that involves ryanodine receptors, Ca2+ sparks and the activation of Ca2+-activated K+ channels.