Point: The muscle pump raises muscle blood flow during locomotion.
Point: The muscle pump raises muscle blood flow during locomotion.
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要点：肌肉泵在运动过程中增加肌肉血流量。
DOI：
10.1152/japplphysiol.00381.2005
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Sheriff,Don
中科院分区：
文献类型：
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作者：
Sheriff,Don
A long-standing gap in our understanding of muscle perfusion during muscular activity has been the huge (2) discrepancy between the levels of blood flow achieved by “maximal” chemical vasodilation or electrically evoked contractions and those achieved during locomotory-type exercise. The classical prevailing thought has been that there must be some unidentified or “missing” vasodilator substance. In 1987, Laughlin (5) proposed that for locomotory-type exercise the muscle pump, via a number of potential mechanisms, could in fact be the missing factor. Perplexingly, studies continue to emerge using electrically evoked contractions to allegedly probe muscle pump function, often providing predictable evidence that the muscle pump does not contribute to active hyperemia in a setting where the pump is proposed not to exist. There are nearly as many models of exercise as there are investigators examining response to muscular activity, ranging from isometric contractions elicited by electrical stimulation of isolated muscles to voluntary, rhythmic, whole body exercises involving all the major muscle groups in the body (2). The contribution of the muscle pump to muscle perfusion is likely to differ among all of these models, ranging from no contribution (indeed an impediment) during an isometric contraction to a presumed peak contribution during upright locomotory exercise (5). The aim here is to identify exercise modes where the muscle pump provides effective support of muscle perfusion.The lumped functions of what is collectively referred to as the “muscle pump” include multiple local and central circulatory effects (12). For example, the expulsion and central mobilization of peripheral venous blood volume raises cardiac filling pressure, stroke volume, and thus cardiac output. In this way the muscle pump makes more blood flow available to be directed to active muscle and thereby indirectly promotes muscle hyperemia. The focus here is on mechanisms by which the muscle pump can directly contribute to muscle hyperemia by acting locally within muscle. A body of circumstantial evidence exists supporting the notion the skeletal muscle circulation processes the proper physiological and anatomical substrate to endow it with the capability for self-perfusion. Muscle blood vessels are well tethered to the surrounding muscle, ensuring that muscle mechanical factors are transmitted to the vasculature (12). Passive changes in muscle length elicit venular length and diameter changes expected for a pump chamber. Application of negative pressure outside muscle (which mimics the proposed sucking action of the muscle pump) rapidly increases arterial inflow (7). The speed with which veins refill from the arterial circulation after muscle relaxation indicates that the muscle pump works like a “bellows pump”(1). Manipulation of stride frequency leads to immediate and proportional changes in muscle blood flow in a setting where vasodilator drive is presumably clamped (13). Finally, when muscle arteries and veins are “short-circuited” and isolated from the remainder of the circulation, rhythmically active muscle readily perfuses itself (16).
