Calcium measurement in isolated arterioles during myogenic and agonist stimulation.
Calcium measurement in isolated arterioles during myogenic and agonist stimulation.
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DOI：
10.1152/ajpheart.1991.261.3.h950
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发表时间：
1991-09
期刊：
影响因子：
--
通讯作者：
G. Meininger;D. Zawieja;Jeff C. Falcone;Michael A. Hill;Joseph P. Davey
中科院分区：
文献类型：
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作者：
G. Meininger;D. Zawieja;Jeff C. Falcone;Michael A. Hill;Joseph P. Davey
在激动剂治疗或压力诱导的刺激离体一级骨骼肌小动脉中的肌源性反应期间测量血管平滑肌钙。从大鼠提睾肌分离具有自发张力的小动脉（40-180微米）并插管。小动脉装载钙敏感染料fura-2，并在340和380 nm处激发。用荧光显微镜形成血管荧光的图像，并使用耦合到低光级相机的图像处理器进行数字化。荧光图像允许在小动脉壁内看到单个血管平滑肌细胞。使用血管壁的荧光强度（表示为340 nm/380 nm处的荧光比率）估计血管壁钙的变化。局部应用去甲肾上腺素（10 μ M）的小动脉引起快速和持续的收缩的小动脉（64%的基底直径）。钙反应是双相的，包括短暂峰值至基础值的271%，随后下降至基础值的143%的新稳态。相比之下，稳态吲哚内酰胺（1 μ M）产生类似程度的收缩，而不增加钙。腺苷使小动脉显著扩张（35%），并使血管壁钙减少（24%）。为了研究肌源性反应，将血管内压从90 cm H2O逐步增加至130 cm H2O。血管内压力增加导致血管直径最初增加约5%，随后主动收缩使直径恢复至基底直径。与这种直径变化相关，估计的血管壁钙迅速增加8 +/- 2%，然后继续缓慢增加，并保持在高于基础水平10-15%的水平。本研究证明了钙显像技术在离体小动脉中的成功应用，以研究钙在小动脉功能中的作用。结果表明，不同的激动剂的钙收缩关系不同，并进一步与压力诱导的血管平滑肌钙的增加在生肌反应过程中的作用一致。
Vascular smooth muscle calcium was measured during agonist treatment or pressure-induced stimulation of the myogenic response in isolated first-order skeletal muscle arterioles. Arterioles (40-180 microns) with spontaneous tone were isolated from rat cremaster muscle and cannulated. Arterioles were loaded with the calcium-sensitive dye fura-2 and excited at 340 and 380 nm. Images of vessel fluorescence were formed with a fluorescence microscope and digitized using an image processor coupled to a low light level camera. The fluorescent images allowed individual vascular smooth muscle cells to be seen within the arteriolar wall. Fluorescent intensity of the vessel wall, expressed as the ratio of fluorescence at 340 nm/380 nm, was used to estimate changes in vessel wall calcium. Topical application of norepinephrine (10 microM) to the arterioles caused a rapid and sustained constriction of the arterioles (64% of basal diam). The calcium response was biphasic consisting of a transient spike to 271% of basal followed by a decrease to a new steady state at 143% of basal. In comparison, steady-state indolactam (1 microM) produced a similar degree of constriction without an increase in calcium. Adenosine significantly dilated (35%) the arterioles and produced a decrease (24%) in vessel wall calcium. To investigate the myogenic response, intravascular pressure was step increased from 90 to 130 cmH2O. Increasing intravascular pressure caused an initial increase in vessel diameter of approximately 5% followed by active constriction that returned diameter to basal diameter. In association with this diameter change, estimated vessel wall calcium increased rapidly 8 +/- 2% and then continued to increase more slowly and remained elevated at 10-15% above basal levels. This study demonstrates the successful application of calcium-imaging technology in isolated arterioles for study of the role of calcium in arteriolar function. Results indicate that the calcium-contraction relationship differs for different agonists and are further consistent with a role for pressure-induced increases in vascular smooth muscle calcium during the myogenic response.