Study of the stimulus-response relationship in a multi-cellular system by use of stretch-induced contractile activation of vascular tissue.

利用拉伸诱导的血管组织收缩激活来研究多细胞系统中的刺激-反应关系。

基本信息

批准号：
63571051
负责人：
NAKAYAMA Koichi
金额：
$ 1.34万
依托单位：
University of Shizuoka
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

The contractile reaction of the vascular smooth muscle in response to mechanical stretch, first observed in isolated segments of canine carotid artery by Bayless in 1902 is often postulated to be a mechanism of myogenic control of blood flow. Studies on stretch-induced tone in vascular tissue touch the core of problems with respect to 1) the mechanisms of transmembrane or cell to cell signal transduction; 2) the interaction between blood and/or endothelium with medial smooth muscle or other vascular components; and 3) the specific role of Ca, i.e., extra- and intracellular Ca components or stretch- sensitive Ca channels. The present experiments were undertaken to elucidate the mechanisms of stretch-induced contraction, with particular reference to the role of Ca and endothelium.Quick stretching of cerebral artery obtained from dog, guinea-pig, rat and cat at a rate of 10 cm/sec to 140% of the slack length of the muscle evoked a delayed contraction, which was always preceded by an incre … More asing cytosolic Ca signals measured by using fura-2. The contraction produced by quick stretch was myogenic in nature, because the response was not affected by autonomic blockers such as phentolamine, propranolol, atropine, or by tetrodotoxin. Furthermore, the contractile response to quick stretch occurred almost equally irrespective of the presence or absence of endothelium, while the endothelium- dependent relaxation produced either by A 23187 in dog or by acetylcholine in cat was abolished when the endothelium was mechanically rubbed from the artery. Hemoglobin (0.01- 0.2 mg/ml), which increased the basal tone by 10-15% of the maximum contracture produced by 80 mM K, potentiated the stretch-induced contraction 2- to 3-fold over the control. The enhanced response to stretch was attenuated by removal of the endothelium and was readily suppressed by Ca antagonists such as nisoldipine as well as diltiazem, indicating that hemoglobin potentiates the contraction upon stretch by promoting transmembrane supply of Ca. The presence of endothelium seems to amplify the vasoconstrictor action of hemoglobin.As to the ionic mechanisms of the stretch-induced tone with special reference to Ca, we also studied whether dual Ca components or stretch-sensitive Ca channel could be dominant in the genesis of the stretch-induced tone. Unlike the contraction produced by high K, which is totally dependent on extracellular Ca, the stretch-induced tone was much more resistant to Ca antagonists and Ca withdrawal. it was necessary to stretch the artery repeatedly in Ca-free medium or in a Ca antagonist-containing medium in order to suppress the stretch-induced tone. Furthermore procaine, dantrolene and ryanodine partially inhibited the tone. Ultramicroscopic studies revealed that in the cerebral artery smooth muscle cells at rest, the pyroantimonate precipitate, an measure of ca was localized along the inner surface of the plasma membrane, while in muscle cells fixed during the stretch- induced contraction the precipitate was diffusely distributed in the myoplasm, indicating that the stretch-induced tone is associated with not only influx of Ca through dihydropyridine-sensitive Ca channel but also Ca release from the inner surface of the plasma membrane.The present results strongly suggest that the genesis of the stretch-induced tone is myogenic in nature. Endothelium seems to modulate the tone, dependent upon the agonistic stimuli applied to the artery. Our studies also suggest that the low susceptibility of the stretch-induced contraction to Ca antagonists is attributable to dual Ca supplies. It is unlikely that a new type of Ca channel, i.e., one which is stretch-sensitive but resistant to Ca antagonist, truly exists in the cerebral artery. Less

血管平滑肌的收缩反应响应机械拉伸，首先在1902年通过Bayless在犬颈动脉的孤立段中观察到，通常被张贴为对血液流动的肌原性控制的机制。关于血管组织中拉伸诱导的张力的研究，相对于1）跨膜或细胞的机制与细胞信号转导的机制有关； 2）血液和/或内皮与培养基平滑肌或其他血管成分之间的相互作用； 3）CA的特定作用，即细胞外CA组件或拉伸敏感CA通道。进行了本实验，以阐明拉伸引起的收缩的机制，特别是指Ca和内皮的作用。从狗，豚鼠，大鼠和猫以10 cm/sec的速度伸展脑动脉的伸展，始终通过延迟的捕获，以延迟的速度逐渐增加，这是在10 cm/sec中获得的，这是一个延迟的ca徒，这是一个延迟的因素，这是在延迟的限制中，这是一个延迟的缩放，以增加…… Fura-2。快速拉伸产生的收缩本质上是肌源性的，因为该反应不受苯丙胺，普萘洛尔，芳香剂或四毒素等自主阻滞剂的影响。此外，对快速拉伸的收缩反应几乎同样同样地存在，而不论存在于森林，而在狗中由23187产生的内皮依赖性弛豫或在机械从疗法中消除猫中的乙酰胆碱在CAT中产生的弛豫。血红蛋白（0.01- 0.2 mg/ml），将基本音调增加了80 mM K产生的最大收缩的10-15％，可能是对照组的拉伸诱导的收缩2-3倍。通过去除内皮来减弱对拉伸的反应，并很容易受到诸如尼索迪地平和diltiazem之类的Ca拮抗剂的抑制，这表明血红蛋白在促进CA的跨膜供应时会在拉伸时的收缩。内皮的存在似乎扩大了血红蛋白的血管收缩作用。由于特别参考CA的拉伸诱导的音调的离子机制，我们还研究了双CA成分还是伸展敏感的Ca通道是否在拉伸诱发的音调的创造中可能占主导地位。与高k产生的收缩完全取决于细胞外Ca，拉伸引起的音调对CA拮抗剂和CA戒断具有更大的抵抗力。为了抑制拉伸诱导的音调，有必要在无CA的培养基或含Ca拮抗剂的培养基中反复拉伸动脉。此外，Procaine，Dantrolene和Ryanodine部分抑制了语调。超显镜研究表明，在静止的大脑动脉平滑肌细胞中，黄金甲酸的精度，Ca的测量沿质膜的内表面定位，而在固定的肌肉细胞中，在拉伸诱导的收缩期间固定的肌肉细胞固定在肌肉中，降水剂在肌层中差异与肌菌株相关，表明肌菌株与肌菌株相关，这与肌菌株相关，这与肌菌株相关，这与肌肉分布相关，这与肌肉细胞相关。二氢吡啶敏感的Ca通道，但也从质膜内表面释放出来。当前的结果强烈表明，拉伸诱导的张力的起源本质上是肌源性的。内皮似乎调节了张力，取决于应用于动脉的激动刺激。我们的研究还表明，拉伸引起的CA拮抗剂的敏感性低归因于双CA供应。一种新型的Ca通道不太可能，即伸展敏感但对CA拮抗剂具有抗性的一种真正存在于脑动脉中。较少的