ROLE OF ENDOTHELIUM DERIVED RELAXING FACTOR IN THE REGULATION OF THE TONE OF THE VENOUS SYSTEM

[目的]多巴胺已被广泛应用于充血性心力衰竭的治疗，但其对血管系统的影响尚未完全阐明。在这项研究中，我们研究了犬离体股动脉和静脉的收缩是否被内皮源性舒张因子（EDRF）所修饰，EDRF是通过刺激内皮细胞中的α 2-肾上腺素受体而释放的。[方法]将犬股动脉和股静脉分别切成5 mm长的带内皮和不带内皮的环状段，悬于37 μ C Krebs-Henseleit液中，记录等长收缩力的变化。[结果与讨论]（1）α_2受体激动剂可乐定（1 × 10 ~（-1）× 10 ~（-1）M）仅收缩静脉，不收缩动脉;用NOS抑制剂NG-硝基-L-精氨酸（L-NA：1 × 10 ~（-1）M）预处理可增强可乐定对静脉的收缩作用，但对动脉的收缩作用不明显，提示这种增强静脉结构的作用是间接的 ...更多信息 d通过激活α 2-肾上腺素受体产生EDRF。(2)多巴胺（1 × 10 ~（-1）× 10 ~（-1）M）使动、静脉均收缩。用L-NA（1 × 10 M）预处理可增强这种收缩，表明多巴胺在动脉和静脉中释放EDRF。(3)去内皮可增强多巴胺对动脉和静脉的收缩作用，但用L-NA（1 × 10 ~（-1）M）预处理后，这种收缩作用消失。(4)多巴胺使静脉收缩，但用α_2-拮抗剂育亨宾（1 × 10 ~（-1）M）预处理可部分抑制多巴胺引起的静脉收缩。用育亨宾和L-NA预处理不影响多巴胺引起的静脉收缩。用育亨宾或育亨宾和L-NA预处理不影响多巴胺对动脉的收缩作用。这些结果表明，多巴胺收缩动脉和静脉，这种收缩是通过激活α 2-肾上腺素受体释放的EDRF的血管舒张作用进行修改。[结论]多巴胺可能通过激活犬离体股动脉和股静脉内皮细胞上的α 2肾上腺素能受体释放EDRF。少

[Purpose]Dopamine has been widely used for the treatment of congestive heart failure, However, effects of dopamine on the vascular system have not yet been fully clarified. In this study, we investigated whether the constriction of the canine isolated femoral arterie and veins are modified by the endothelium derived relaxing factor (EDRF) which is released via the stimulation of alpha2 -adrenoceptors in the endothelium.[Method]Canine isolated femoral arteries and veins which were cut into 5 mm long ring segments with and without endothelium were suspended in 37ﾟC Krebs-Henseleit solution, and the changes in isometric force were recorded.[Results and Discussion](1)alpha2-agonist, clonidine (1X10 - 1X10 M) constricted only the veins, but not the arterles. Pretreatment with NOS inhibitor, NG-nitro-L-arginine (L-NA : 1X10 M) potentiated the constriction of the vein, but not of the arteries, exerted by clonidine, suggesting that this potentiation of the construction of the veins was mediate … More d through the production of EDRF via the activation of alpha2-adrernoceptors. (2) Dopamine (1X10 - 1X10 M) constricted both the arterie and veins. This constriction was potentiated by the pretreatment with L-NA (1X10 M), suggesting that dopamine releases EDRF in both the arteries and veins. (3) Removal of endothelium potentiated the dopamine-induced constriction of the arteries and veins, however, after the pretreatment with L-NA (1X10 M), this constriction was not observed.(4) Dopamine constricted the veins, although pretreatment with alpha2-antagonist, yohimbine((1X10 M) partially inhibited the constriction of the vein exerted by dopamine. Pretreatment with both yohimbine and L-NA did not affect the constriction of the vein exerted by dopamine. Pretreatment with yohimbine or both yohimbine and L-NA did not affect the constriction of the arteries exerted by dopamine. These results suggest that dopamine constricts both the arteries and veins and that this constriction is modified by the vasodilatory action of EDRF released via the activation of alpha2-adrenoceptors.[Conclusion]It is suggested that dopamine releases EDRF via the activation of alpha2-adrenoceptors on the endothelium in the canine isolated femoral arteries and veins. Less