Reber K M, Nowicki P T
Department of Pediatrics, Children's Hospital, Columbus, Ohio 43205, USA.
Am J Physiol. 1998 Feb;274(2):G290-8. doi: 10.1152/ajpgi.1998.274.2.G290.
The responses of buffer-perfused terminal mesenteric arteries from 3- and 35-day-old swine to manipulation of intravascular pressure and flow rate were determined. Under in vivo conditions, these vessels demonstrated age-dependent differences in resting diameter (182 vs. 301 microns in 3- vs. 35-day-old swine). A proximal-to-distal pressure gradient was present in vessels from both age groups (delta 13 vs. delta 16 mmHg in 3- vs. 35-day-old swine), suggesting their functional role as resistance vessels. Vessels were mounted within an in vitro perfusion apparatus that allowed independent regulation of inflow and outflow pressure. Vessels from both age groups demonstrated the development of active tone in response to an incremental rise in pressure, applied in the absence of flow. However, myogenic vasoconstriction was only observed in younger arterioles. Similarly, both groups demonstrated dilation in response to a flow stimulus generated in the absence of a net change in intravascular pressure, although the magnitude of this response was significantly greater in younger vessels (+27 vs. +7% in 3- vs. 35-day-old swine). The dilatory response to flow was eliminated by NG-monomethyl-L-arginine (10(-4)M) but restored by coadministration of L-arginine (10(-3)M). Myogenic vasoconstriction was overridden by flow-mediated dilation in terminal mesenteric arteries from 3- but not 35-day-old swine after concomitant application of pressure and flow stimuli. We conclude that the hemodynamic characteristics of terminal mesenteric arteries are age dependent in postnatal swine.
测定了3日龄和35日龄猪的缓冲液灌注肠系膜终末动脉对血管内压力和流速变化的反应。在体内条件下，这些血管在静息直径上表现出年龄依赖性差异（3日龄猪为182微米，35日龄猪为301微米）。两个年龄组的血管均存在近端至远端的压力梯度（3日龄猪为13 mmHg，35日龄猪为16 mmHg），表明它们作为阻力血管的功能作用。将血管安装在体外灌注装置中，该装置可独立调节流入和流出压力。两个年龄组的血管在无血流情况下压力逐渐升高时均表现出主动张力的发展。然而，仅在较年轻的小动脉中观察到肌源性血管收缩。同样，两组在血管内压力无净变化时对血流刺激均表现出扩张，尽管较年轻血管的这种反应幅度明显更大（3日龄猪为+27%，35日龄猪为+7%）。对血流的扩张反应被NG-单甲基-L-精氨酸（10(-4)M）消除，但通过同时给予L-精氨酸（10(-3)M）得以恢复。在同时施加压力和血流刺激后，3日龄猪的肠系膜终末动脉中血流介导的扩张可克服肌源性血管收缩，而35日龄猪则不然。我们得出结论，出生后猪的肠系膜终末动脉的血流动力学特征具有年龄依赖性。
