ENDOTHELIUM-DEPENDENT, FLOW-INDUCED DILATION OF ISOLATED CORONARY ARTERIOLES
ENDOTHELIUM-DEPENDENT, FLOW-INDUCED DILATION OF ISOLATED CORONARY ARTERIOLES
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DOI：
10.1152/ajpheart.1990.259.4.h1063
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发表时间：
1990-10-01
影响因子：
--
通讯作者：
CHILIAN, WM
中科院分区：
文献类型：
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作者：
KUO, L;DAVIS, MJ;CHILIAN, WM
在大导管冠状动脉中已记录了流量介导的扩张，但在冠状小动脉中未记录。本研究的目的是确定这种反应是否发生在冠状动脉，以及它是否与肌源性收缩竞争。分离心外膜下小动脉（40-80 μ m），并用连接到独立储液器系统的两个玻璃微量移液管插管。在零流量，肌源性反应进行了研究，在20和140厘米水柱之间的管腔内压力（IP）的范围内。当IP增加（> 60 cmH 2 O）和减少（< 60 cmH 2 O）时，分别观察到肌源性收缩和扩张。通过在相等和相反的方向上同时移动储存器来启动流动，从而产生压力梯度（Δ P）而不改变平均管腔压力（范围Δ P = 4-60 cm H2O）。通过将IP分别设置为20、60和100 cmH 2 O，在低、中和高肌源性张力下研究了流动诱导的反应。流动诱导的扩张的阈值为Δ P = 4cmH 2 O，在Δ P = 20 cmH 2 O时观察到最大扩张。在Δ P为4和60 cmH 2 O时，分离的小动脉中的红细胞速度为1.2 ± 0.001。0.2和15.9 .+-。1.3 mm/s，这是在体内冠状动脉微血管报告的范围内。流量引起的扩张的幅度在中间音（60 cmH 2 O IP）时最大，但在较低和较高IP时减弱。机械去除内皮后，自发张力和肌源性反应得以保留，但血流诱导的扩张和缓激肽诱导的扩张被废除。因此，压力依赖性和流量介导的反应都发生在孤立的冠状动脉，但只有流量介导的反应需要一个完整的内皮。我们推测这两种机制在生理条件下相互作用以调节冠状动脉微血管张力。
Flow-mediated dilation has been documented in large conduit coronary arteries but not in coronary arterioles. The goal of this study was to determine whether this response occurs in coronary arterioles and whether it competes with myogenic constriction. Subepicardial arterioles (40-80 .mu.m) were isolated and cannulated with two glass micropipettes connected to independent reservoir systems. During zero flow, myogenic responses were studied over the range of intraluminal pressure (IP) between 20 and 140 cmH2O. Myogenic constrictions and dilations was observed when IP was increased (> 60 cmH2O) and decreased (< 60 cmH2O), respectively. Flow was initiated by simultaneously moving the reservoirs in equal and opposite directions, thus generating a pressure gradient (.DELTA.P) without changing the mean luminal pressure (range .DELTA.P = 4-60 cm H2O). Flow-induced responses were studied at low, intermediate, and high myogenic tones by setting IP at 20, 60, and 100 cmH2O, respectively. The threshold for flow-induced dilation was .DELTA.P = 4 cmH2O, and maximum dilation was observed at .DELTA.P = 20 cmH2O. Red cell velocities in isolated arterioles at .DELTA.P of 4 and 60 cmH2O were 1.2 .+-. 0.2 and 15.9 .+-. 1.3 mm/s, respectively, which are within the range of those reported for coronary microvessels in vivo. The magnitude of the flow-induced dilation was greatest at the intermediate tone (60 cmH2O IP) but was attenuated at lower and higher IP. After mechanical removal of the endothelium, spontaneous tone and myogenic responses were preserved, but flow-induced dilation and bradykinin-induced dilation were abolished. Therefore, both pressure-dependent and flow-mediated responses occur in isolated coronary arterioles, but only flow-mediated responses require an intact endothelium. We speculate that these two mechanisms interact under physiological conditions to modulate coronary microvascular tone.