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

人体的体温是由热量散失控制的，因为皮肤在高温下有大量的血液流动和汗液。然而，由于直立体位时皮肤血管中的血液淤积和因失汗引起的低血容量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舒张。最近，我们提出了与心脏周期同步的皮肤交感神经活动（SSNA）的一个组成部分是皮肤血流的气压反射控制的传出途径；然而，它可能包含肌肉交感神经活动（MSNA）。在这里，我们发现在体温过高的男性中，随着头部向上倾斜，SSNA成分减少，而MSNA成分增加。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.