Frisbee J C, Roman R J, Falck J R, Linderman J R, Lombard J H
Department of Physiology, Milwaukee, Wisconsin 53226, USA.
Microvasc Res. 2000 Jul;60(1):37-48. doi: 10.1006/mvre.2000.2245.
The effects of elevated PO(2) on flow-induced dilation of in situ skeletal muscle arterioles was assessed in cremaster muscle preparations from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Blood flow increases in selected arterioles were initiated by occlusion of a parallel daughter branch from a parent arteriole. Changes in the diameter of the perfused arteriole were measured with a video micrometer and erythrocyte velocity was measured using optical Doppler velocimetry. Superfusate PO(2) was controlled by changing the O(2) concentration (0% O(2) or 21% O(2)) of the equilibration gas mixture. The increase in arteriolar diameter during occlusion was reduced in SHR compared to WKY rats, resulting in an elevated wall shear rate in SHR. Elevated PO(2) decreased flow-induced dilation in both groups and increased wall shear rate during parallel occlusion. An inhibitor of the formation of 20-HETE via cytochrome P450-4A enzymes (P450), dibromododecenyl methylsulfimide, minimized O(2)-induced constriction of arterioles and prevented the O(2)-induced decrease in flow-induced dilation and the increase in wall shear rate in both SHR and WKY rats. These results suggest that: (1) flow-induced dilation of in situ skeletal muscle arterioles is impaired in SHR compared to WKY, (2) elevated O(2) compromises flow-induced dilation in both groups, (3) 20-HETE contributes to both the O(2)-induced increases in resting tone and the reduced flow-induced dilation of cremasteric arterioles with elevated PO(2).
在来自自发性高血压大鼠（SHR）和血压正常的Wistar-Kyoto（WKY）大鼠的提睾肌制备物中，评估了升高的PO₂对原位骨骼肌小动脉血流诱导性扩张的影响。通过阻断来自母小动脉的平行子分支来启动选定小动脉中的血流增加。用视频测微计测量灌注小动脉的直径变化，并用光学多普勒测速仪测量红细胞速度。通过改变平衡气体混合物的O₂浓度（0% O₂或21% O₂）来控制超滤液PO₂。与WKY大鼠相比，SHR中阻断期间小动脉直径的增加减少，导致SHR中的壁面剪切率升高。升高的PO₂降低了两组中的血流诱导性扩张，并在平行阻断期间增加了壁面剪切率。一种通过细胞色素P450-4A酶（P450）抑制20-HETE形成的抑制剂，二溴十二碳烯基甲基磺酰亚胺，使O₂诱导的小动脉收缩最小化，并防止了O₂诱导的血流诱导性扩张降低以及SHR和WKY大鼠中壁面剪切率的增加。这些结果表明：（1）与WKY相比，SHR中原位骨骼肌小动脉的血流诱导性扩张受损；（2）升高的O₂损害了两组中的血流诱导性扩张；（3）20-HETE促成了O₂诱导的静息张力增加以及PO₂升高时提睾肌小动脉血流诱导性扩张的降低。
