Vascular control in the colon and rectum.
Vascular control in the colon and rectum.
复制标题
结肠和直肠的血管控制。
DOI：
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发表时间：
1984
影响因子：
1.9
通讯作者：
Andersson Po
中科院分区：
文献类型：
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作者：
Andersson Po
在“静止”状态下，大肠和小肠的血流量及其壁内分布似乎非常相似，但这两个内脏的循环调节存在一些明显的差异。血液流动的自动调节在肠道的大多数区域中发展良好，除了结肠，其中总血流量随动脉血压变化很大。然而，结肠自动调节能力可以通过增加组织的代谢需求来改善，例如通过营养物的腔内放置。代谢和生肌因素似乎是相互负责的自动调节行为在大肠。功能性血管舒张发生在大肠中，以响应增加的代谢，这是一种可以例如通过腔内放置挥发性脂肪酸引起的反应。近端结肠粘膜的机械刺激也引起局部充血反应，推测其通过可能释放5-HT的内在神经反射介导。在远端结肠和直肠中，机械刺激引起更广泛的充血，据报道这是血管活性肠多肽（VIP）作为可能的介质的骨盆-骨盆反射的结果。交感-肾上腺系统的激活引起大肠阻力和电容血管的收缩。交感神经活动的反射增加，如在运动或出血中，导致流量的重新分配和血液从大肠到其他组织的动员，从而在压力情况下，促进更重要器官如心脏和大脑的循环。大肠的最远端部分，特别是直肠，似乎有一个独特的外源性血管扩张控制通过副交感神经盆腔神经。这些神经的激活在直肠中引起非常明显且维持良好的血管扩张反应，但在远端结肠中仅为短暂的反应。这种神经血管舒张反应几乎不受毒蕈碱阻滞的影响，因此本质上基本上是非胆碱能的。VIP在盆腔神经刺激期间从结肠和直肠释放，直肠输出量特别大并且在时间上与伴随的血管舒张良好相关。直肠血管对VIP非常敏感，动脉内输注这种肽引起的血管反应与盆腔神经刺激非常相似。这些证据表明VIP可能是负责大肠最远端非胆碱能血管舒张的神经递质。
: Blood flow and its intramural distribution in the large and small intestines 'at rest' appear to be quite similar, but there are some obvious differences in the regulation of the circulation in these two viscera. Autoregulation of blood flow is well developed in most regions of the gut, with the exception of the colon in which total blood flow varies greatly with arterial blood pressure. However, the colonic autoregulatory capacity can be improved by increasing the metabolic demand of the tissue, e.g. by intra-luminal placement of nutrients. Metabolic and myogenic factors seem to be mutually responsible for autoregulatory behaviour in the large intestine. Functional vasodilatation occurs in the large intestine in response to increased metabolism, a reaction which can be evoked for instance by intra-luminal placement of volatile fatty acids. Mechanical stimulation of the mucosa in the proximal colon also elicits a local hyperaemic response which is postulated to be mediated via an intrinsic nervous reflex possibly releasing 5-HT. In the distal colon and the rectum mechanical stimulation evokes a more wide-spread hyperaemia which is reported to be the result of a pelvo -pelvic reflex with vasoactive intestinal polypeptide (VIP) as a possible mediator. Activation of the sympatho-adrenal system causes constriction of the large intestinal resistance and capacitance vessels. Reflex increase in sympathetic activity, as in exercise or haemorrhage, causes a redistribution of flow and a mobilization of blood from the large intestine to other tissues, thereby, in stress situations, promoting the circulation in more vital organs such as the heart and brain. The most distal part of the large intestine, in particular the rectum, seems to have a unique extrinsic vasodilator control via the parasympathetic pelvic nerves. Activation of these nerves elicits a very pronounced and well maintained vasodilator response in the rectum but only a transient one in the distal colon. This neural vasodilator response is little affected by muscarinic blockade and, hence, largely non-cholinergic in nature. VIP is released from the colon and rectum during pelvic nerve stimulation, the rectal output being especially large and well correlated in time to the concomitant vasodilatation. The rectal vessels are very sensitive to VIP, and intra-arterial infusion of this peptide causes a vascular response which closely resembles that of pelvic nerve stimulation. Such evidence indicates that VIP might be the neurotransmitter responsible for the non-cholinergic vasodilatation in the most distal part of the large intestine.