Roles of skin sympathetic nerve activity synchronized with cardiac cycle in baroreflex control of skin blood flow in hyperthermic humans

人体的体温是由热中的大量皮肤血液流动和汗水散热控制的。然而，由于皮肤血管中的血液在直立位置聚集，以及因汗水流失而导致的血容量减少，减少了静脉回流到心脏，这威胁到血压的维持。为了防止这种情况，通过压力反射抑制皮肤血管扩张。最近，我们提出与心动周期同步的皮肤交感神经活动(SSNA)成分是压力感受性反射控制皮肤血流的传出通路，但它可能含有肌交感神经活动(MSNA)。在这里，我们发现，在体温过高的男性中，SSNA成分随着头朝上倾斜而减少，而MSNA成分则增加。因此，该组件不太可能包含MSNA。

Body temperature in humans is controlled by heat dissipation due to large amounts of skin blood flow and sweat in the hot. However, since blood pooling in skin vessels in an upright position and hypovolemia due to sweat loss decrease venous return to the heart, it threatens blood pressure maintenance. To prevent this, skin vasodilation is suppressed through baroreflexes. Recently, we suggested that a component of skin sympathetic nerve activity (SSNA) synchronized with cardiac cycle was an efferent path of the baroreflex control of skin blood flow; however, it might contain muscle sympathetic nerve activity (MSNA). Here, we found in hyperthermic men that the SSNA component decreased while MSNA increased with head-up tilt. Thus, the component unlikely contains MSNA.