ROLES BIOACTIVE PEPTIDE IN EXERCISE-INDUCED REDISTRIBUTION OF TISSUE BLOOD FLOW OF INTERNAL ORGANS AND MUSCLES

内皮素-1(ET-1)是一种血管收缩多肽。运动导致组织血流量的重新分配，从而增加了活跃肌肉的血流量，而减少了内脏循环(如肾脏和脾)的血流量。我们以前曾报道，剧烈运动会导致内脏组织中ET-1的产生增加，然后我们假设ET-1参与了运动引起的组织血流量的重新分配。本实验观察了急性阻断ET_A受体对运动大鼠局部组织血流量的影响。用微球法测定ET_A受体拮抗剂(TA-0201)或赋形剂(n=7)处理30min前和30min时的局部血流量。TA-0201组大强度运动引起的肾、脾血流量下降幅度明显小于TA-0201组(肾脏：36.8±7.1比66.9±5.2%)。P&lt；0.01，脾：31.6±6.8，57.1±9.2%。P&lt；0.05)。此外，经TA-0201预处理的大强度运动引起的主动肌肉血流量的增加明显少于用药组(胫前肌：223.7±36.6vs.423.1±83.0%，p&lt；0.05)。本研究提示，ET-1介导的血管收缩参与了运动中大鼠肾、脾血流量的减少，从而增加了活动肌肉的血流量。

Endothelin-1 (ET-1) is a vasoconstrictor peptide. Exercise results in redistribution of tissue blood flow, by which blood flow in increased in active muscles, whereas it is decreased in visceral circulation (such as in kidneys and spleen). We previously reported that an intense exercise causes the increase of ET-1 production in the internal organs, then, we hypothesized that ET-1 participates in the exercise-induced redistribution of tissue blood flow. We investigated the effects of acute ET_A receptor blockade on regional tissue blood flow during exercise in rats. Regional blood flow was measured using microsphere technique before and during treadmill running of 30 min duration under pretreatment with ET_A receptor antagonist (TA-0201) or vehicle (both n=7). The decreases in blood flows to the kidney and spleen induced by intense exercise under pretreatment with TA-0201 were significantly less compared with those under pretreatment with TA-0201 were significantly less compared with those under pretreatment with vehicle (kidney : 36.8 ± 7.1 vs. 66.9 ± 5.2 %. p<0.01, spleen : 31.6 ± 6.8 vs. 57.1 ± 9.2 %. p<0.05). Furthermore, the increases in blood flows to the active muscles induced by intense exercise under pretreatment with TA-0201 were significantly less compared with those under pretreatment with vehicle (tibialis anterior muscle : 223.7 ± 36.6 vs. 423.1 ± 83.0 %, p<0.05). The present study suggests that ET-1-mediated vasoconstriction participates in the decrease of blood flow in the kidneys and spleen of rats during exercise, thereby contributing to the increase of blood flow in the active muscles.