【摘要】 在27只隔离灌流颈动脉窦区的麻醉大鼠，观察了内皮素（ET-1）对动脉压力感受器反射的调制作用。结果如下：（1）在颈动脉窦区灌流1nmol／L的ET-1时，压力感受器机能曲线向左下方移位，曲线的最大斜率（PS）由0.40±0.02增至0.51±0.02kPa／kPa（P＜0.01），压力感受器反射性血压下降幅度（RD）由5.66±0.23增至6.76±0.22kPa（P＜0.01）。由此提示，这一剂量的FT-1对压力感受器反射有易化作用。（2）用10nmol／L的ET-1灌流时，压力感受器机能曲线则向右上方移位，PS降至0.28±0.01kPa／kPa（P＜0.01），RD降至4．16±0.19kPa（P＜0.01）；100nmol／L的ET-1可使压力感受器机能曲线向右上方移位更为明显，PS降至0.19±0.03kPa（P＜0.001），RD进一步降至3.33±0.38kPa（P＜0.001）。这些结果表明，上述两种剂量的ET-1对压力感受器反射有抑制作用。（3）ETA受体选择性阻断剂BQ123（0.15μmol／L）可以阻断ET-1（10nmol／L）对压力感受器反射的抑制效应。（4）预先灌流KATP通道阻断剂格列苯脲（10μmol／L），也可阻断ET-1的效应。综上所述，ET-1对压力感受器反射有双重效应，低剂量时有易化作用，而较高剂量时则有抑制作用，后一作用由ET-1型受体介导并有KATP通道的参与。更多还原

【Abstract】 Modulatory effects of endothelin (ET) on carotid harorellex were examined in 27 anesthetized rats With isolated carotid sinus perfusion. The results obtained were as follows: (1) By perfusing with 1 nmol/L ET-1, the functional curve of carotid baroreflex (FCCB) was shifted to the left and downward with an increase in its peak slope (PS)from 0.40±0.02 to 0.51±0.02 kPa/kPa (P<0.01), while the reflex decrease of mean arterial pressure (RD) was increased from 5. 66±0. 23 to 6.76±0.22 kPa (P<0.01). The above results indicated that this dose of ET-1 facilitated the carotid baroreflex. (2) On the contrary, by perfusing with 10 nmol/L of ET-1, FCCB was shifted to the right and upward with a dearease of PS to 0.28±0.01 kPa/kPa (P<0.01), while RD was decreased to 4. 16±0. 19 kPa (P<0.01). In response to perfusion with 100 nmol/L ET-1,FCCB was further shifted to the right and upward with a marked decrease of PS to 0.19±0.03 kPa/kPa(P<0.001), and RD was conspicuously decreased to 3.33±0.38 kPa (P< 0.001). These results showed that ET-1 at the doses of 10 or 100 nmol/L exerted an inhibitoly action on baroreflex. (3)Selective ETA receptor blocker BQ123 (0.15 μmol/L) might abolish the effects of ET-1 (10 nmol/L) on baroreflex. (4) Prepefusing with KATP channel antagonist glibenclamide (10 μmol/L) could also eliminated the effects of ET-1. Taken together, it is suggested that ET-1 exerts a dual effects on baroreflex, being facilitatory at lower dose and inhibitory at higher dose. The latter effect is mediated by ETA receptor, in which KATP channels may be involved.更多还原