Borgström P, Lindbom L, Meyer J U, Sjöquist M, Arfors K E, Intaglietta M
Pharmacia Experimental Medicine, La Jolla, California 92037.
Int J Microcirc Clin Exp. 1990 May;9(2):175-86.
Transverse (TR) and terminal (TE) arteriolar diameters and TR pressure were measured in the rabbit tenuissimus muscle during steady state reductions in perfusion pressure. An inflatable occluder was positioned on the abdominal aorta proximal to the bifurcation to alter perfusion pressure. In the control conditions, TEs exhibited highly regular cyclic activity (20 +/- 4 cpm). In contrast, TRs seldom exhibited regular vasomotor activity. Pressure reductions from 76 +/- 1 to 40-50 mm Hg caused no significant change in the observed hemodynamic variables. Reductions below this level caused proportional dilations of TRs and a change in vasomotion pattern of TEs; i.e. the fundamental frequency was unaltered, but periods without vasomotion increased in duration. At an arterial pressure of 30-40 mm Hg, vasomotion in the TEs completely disappeared. Pressure in the distal TR was autoregulated at 40 +/- 4 mm Hg until a threshold (40-50 mm Hg) was reached; thereafter TR pressure decreased in proportion to the arterial pressure decrements. These results suggest that the TRs are the last generation of arterioles involved in the autoregulation of microvascular pressure. Furthermore, the basic frequency and maximal amplitude of vasomotion in TEs are not affected by pressure reductions.
在灌注压稳态降低期间，测量了兔股薄肌的横向（TR）和终末（TE）小动脉直径以及TR压力。在腹主动脉分叉近端放置一个可充气阻塞器以改变灌注压。在对照条件下，TE表现出高度规则的周期性活动（20±4次/分钟）。相比之下，TR很少表现出规则的血管运动活动。灌注压从76±1毫米汞柱降至40 - 50毫米汞柱时，观察到的血流动力学变量无显著变化。低于此水平的降低导致TR成比例扩张以及TE血管运动模式改变；即基本频率未改变，但无血管运动的时间段持续时间增加。在动脉压为30 - 40毫米汞柱时，TE中的血管运动完全消失。远端TR的压力自动调节至40±4毫米汞柱，直至达到阈值（40 - 50毫米汞柱）；此后TR压力与动脉压降低成比例下降。这些结果表明，TR是参与微血管压力自动调节的最后一代小动脉。此外，TE中血管运动的基本频率和最大幅度不受压力降低的影响。
