刘宜先, 张浩, 马会杰, 何瑞荣
在36只隔离灌流颈动态窦区的麻醉大鼠上,观察了八肽胆囊收缩素(CCK-8)对颈动脉窦压力感受器反射的影响。其结果如下:(1)以CCK-8(0.1、0.5、1.0 #mu#mol/L)隔离灌流颈动脉窦区时,压力感受器机能曲线向右上方移位,曲线最大斜率(PS)减小,反射性血压下降幅度(RD)减少,阈压(TP)和饱和压(SP)均增高。其中RD、PS和TP呈明显的剂量依赖性;(2)用CCK-8的非特异性受体拮抗剂丙谷胺(100 #mu#mol/L)预处理后,能明显减弱CCK-8(0.5 #mu#mol/L)对压力感受器反射的抑制;(3)预先灌流一氧化氮合酶(NOS)阻断剂(L-NAME,100 #mu#mol/L),不能阻断CCK-8(0.5 #mu#mol/L)对压力感受器反射的影响;(4)用Ca~(2+)通道激动剂Bay K 8644(500 nmol/L)预处理后,也能明显减弱CCK-8(0.5 #mu#mol/L)对压力感受器反射的抑制作用。以上结果提示,CCK-8是通过作用于颈动脉窦压力感受器神经元末梢上的受体而起到抑制作用的,其机制可能为抑制了牵张敏感性通道,致使Ca~(2+)离子内流减少,而与内皮细胞释放NO无关。
关键词： cholecystokinin octapeptide (CCK-8); proglumide; Bay K 8644; baroreflex; L-NAME; mean arterial pressure
Cholecystokinin octapeptide inhibits carotid sinus baroreflex in anesthetized rats
Liu Yixian, Zhang Hao, Ma Huijie, He Ruirong
Department of Physiology,Institute of Basic Medicine,Hebei Medical University.Shijiazhuang 050017,Hebei
The results obtained are as follows: (1) By perfusion with CCK-8 (0.1, 0.5, 1.0 #mu#mol/L), the functional curve of baroreflex was shifted to the right and upward, with a decrease in peak slope (PS) (P<0.001) and a reflex decreased (RD) in mean arterial pressure, while the threshold pressure (TP) and saturation pressure (SP) were significantly increased. Among the functional parameters of carotid sinus baroreflex, the changes in RD, PS and TP were dose-dependent. (2) Pretreatment with proglumide (100 #mu#mol/L), a nonselective CCK receptor antagonist, the inhibitory effect of CCK-8 (0.5 #mu#mol/L) on the baroreflex was significantly attenuated. (3) Pretreatment with L-NAME (100 #mu#mol/L), an inhibitor of nitric oxide (NO) synthase, did not affect the inhibitory action of CCK-8 (0.5 #mu#mol/L). (4) Preperfusion with Bay K 8644 (500 nmol/L), an agonist of calcium channel, could attenuate the effect of CCK-8 (0.5 #mu#mol/L). It is suggested that the inhibitory action of CCK-8 on the baroreflex may be mediated by the activation of its receptors in the carotid sinus baroeceptor, leading to an inhibition of stretch-sensitive channels and a decrease in Ca~(2+) influx. However, NO released from the endothelium seems not to be involved in the mechanism of this effect.
Key words: 八肽胆囊收缩素;丙谷胺;Bay K 8644;压力感受器反射;L-NAME;平均动脉压
刘宜先, 张浩, 马会杰, 何瑞荣. 八肽胆囊收缩素对大鼠颈动脉窦压力感受器反射的抑制作用[J]. 生理学报 2004; 56 (1): .
Liu Yixian, Zhang Hao, Ma Huijie, He Ruirong. Cholecystokinin octapeptide inhibits carotid sinus baroreflex in anesthetized rats. Acta Physiol Sin 2004; 56 (1): (in Chinese with English abstract).