Gosche J R, Harris P D, Garrison R N
Department of Surgery, University of Louisville, Kentucky, USA.
Microcirculation. 1996 Dec;3(4):395-400. doi: 10.3109/10739689609148312.
We previously reported differences in intestinal arteriolar responses of adult and suckling rats to three stressors (hemorrhage, hypoxia, and hypothermia) that decreased intestinal blood flow. The small, premucosal arterioles of adult rats dilated in response to all three stressors, whereas the premucosal arterioles of suckling rats constricted or remained unchanged. One explanation for this difference might be absence of myogenic responsiveness in the premucosal arterioles of the immature rat.
We used in vitro videomicroscopy to observe the intestinal arteriolar responses to venous pressure elevation (a myogenic stimulus) in adult (8- to 12-week-old) and suckling (8- to 12-day-old) Sprague-Dawley rats. We increased portal venous pressure by 25 and 50% above the baseline pressure.
Arterioles in the rats displayed the expected "myogenic" response to venous pressure elevation (diameters decreased 12-29% when venous pressure was increased by 50%). In contrast to adult rats, arterioles in the suckling rats failed to constrict in response to increases in venous pressure (diameters increased 14-21% in response to a 50% increase in venous pressure).
These results suggest that the myogenic constrictor mechanisms for control of the microcirculation appear to be either nonfunctional or suppressed in the intestinal microcirculation of suckling rats.
我们之前报道过成年大鼠和乳鼠的肠小动脉对三种降低肠血流量的应激源（出血、缺氧和低温）的反应存在差异。成年大鼠的小的黏膜前小动脉对所有三种应激源均扩张，而乳鼠的黏膜前小动脉则收缩或保持不变。这种差异的一种解释可能是未成熟大鼠的黏膜前小动脉缺乏肌源性反应性。
我们使用体外视频显微镜观察成年（8至12周龄）和乳鼠（8至12日龄）Sprague-Dawley大鼠的肠小动脉对静脉压升高（一种肌源性刺激）的反应。我们将门静脉压在基线压力之上提高25%和50%。
大鼠的小动脉对静脉压升高表现出预期的“肌源性”反应（当静脉压升高50%时，直径减小12%至29%）。与成年大鼠相反，乳鼠的小动脉对静脉压升高没有收缩反应（当静脉压升高50%时，直径增加14%至21%）。
这些结果表明，在乳鼠的肠微循环中，用于控制微循环的肌源性收缩机制似乎不起作用或受到抑制。
