Granger H J, Goodman A H, Granger D N
Circ Res. 1976 May;38(5):379-85. doi: 10.1161/01.res.38.5.379.
The effects of reduction in perfusion pressure, arterial hypoxia, muscle contraction, and adrenergic stimulation on the hindlimb muscle circulation were studied. Under normal conditions (venous PO2 greater than or equal to 40 mm Hg), oxygen delivery to the muscle was maintained mainly by large increases in the capillary exchange capacity and the oxygen extraction ratio in accord with tissue demand following the application of the above stresses. The participation of the resistance vessels under these conditions was minimal. The prevailing venous oxygen tension then was reduced by several means and the response of vascular resistance and capillary exchange capacity to the same stresses was reexamined. At the lower prevailing venous PO2, the sensitivity of the resistance vessels to metabolic and hemodynamic disturbances was greatly increased. Consequently, blood flow autoregulation, functional hyperemia, and hypoxic hyperemia were more intense when venous oxygen tension was low. In contrast, the contribution of exchange capacity was diminished, probably owing to the fact that most of the capillaries already are open at low venous PO2. These data suggest that the locus of local microvascular control of muscle oxygenation shifts from the normally more sensitive precapillary sphincters to the proximal flow-controlling arterioles as the prevailing venous oxygen tension falls. Yet, although the relative contribution of the resistance and exchange vessels to intrinsic regulation of tissue oxygenation is related to the prevailing venous oxygen tension, the two compensatory mechanisms operating in concert maintain tissue PO2 above the critical level over a wide range of stresses.
研究了灌注压降低、动脉缺氧、肌肉收缩和肾上腺素能刺激对后肢肌肉循环的影响。在正常情况下（静脉血氧分压大于或等于40 mmHg），随着上述应激因素的施加，根据组织需求，肌肉的氧输送主要通过毛细血管交换能力和氧摄取率的大幅增加来维持。在这些情况下，阻力血管的参与程度最小。然后通过几种方法降低了当时的静脉血氧张力，并重新检查了血管阻力和毛细血管交换能力对相同应激因素的反应。在较低的当时静脉血氧分压下，阻力血管对代谢和血流动力学紊乱的敏感性大大增加。因此，当静脉血氧张力较低时，血流自动调节、功能性充血和低氧性充血更为强烈。相比之下，交换能力的贡献减弱，这可能是因为在低静脉血氧分压下大多数毛细血管已经开放。这些数据表明，随着当时静脉血氧张力的下降，肌肉氧合的局部微血管控制位点从通常更敏感的毛细血管前括约肌转移到近端流量控制小动脉。然而，尽管阻力血管和交换血管对组织氧合内在调节的相对贡献与当时的静脉血氧张力有关，但这两种协同作用的代偿机制在广泛的应激范围内将组织血氧分压维持在临界水平以上。
