Ca^(2+)在链霉素对大鼠颈动脉窦压力感受器反射影响中的作用  

Role of calcium in the mechanism underlying the inhibitory effect of streptomycin on carotid sinus baroreflex in rats

作　　者：秦晓梅[1] 何瑞荣[1] 

机构地区：[1]河北医科大学基础医学研究所生理室,石家庄050017

出　　处：《生理学报》2000年第6期463-467,共5页Acta Physiologica Sinica

摘　　要：在 2 3只隔离灌流颈动脉窦区的麻醉大鼠上 ,观察了链霉素 (streptomycin ,SM)对动脉压力感受器反射影响的离子机制。结果 :(1)用SM (2 0 0 μmol/L)隔离灌流大鼠颈动脉窦区时 ,压力感受器机能曲线向右上方移位 ,曲线最大斜率及反射性血压下降幅度均减小 (P <0 0 1) ,提示SM对压力感受器反射有抑制作用 ;(2 )预先灌流高Ca2 +溶液 (4mmol/L)后 ,可部分消除SM (2 0 0 μmol/L)对压力感受器反射的抑制作用 (P <0 0 1) ,使其压力感受器机能曲线向左下方移位 ,曲线的最大斜率由 0 2 7± 0 0 4增至 0 37± 0 0 2 (P <0 0 1) ,反射性血压下降幅度由4 32± 0 14kPa增至 6 18± 0 17kPa (P <0 0 1) ,而阈压和饱和压则分别从 10 2 9± 0 2 9和 2 7 2 6± 0 42kPa降至9 98± 0 33和 2 5 2 2± 0 38kPa (P <0 0 5 ) ;(3)用Ca2 +通道激动剂BayK 86 44 (5 0 0nmol/L)预处理 ,可完全消除SM(2 0 0 μmol/L)对压力感受器反射的抑制效应 ;(4 )预先给予Ca2 +激活性K+通道阻断剂 (charybdotoxin ,ChTX ,10 0nmol/L) ,对压力感受器反射无明显影响 ,加入SM后仍呈现抑制作用。以上结果表明 ,SM可能是通过抑制颈动脉窦压力感受器中机械敏感性通道的Ca2 +内流而发挥作用。The effect of streptomycin (SM) on carotid baroreflex was examined in 23 anesthetized rats with isolated carotid sinus perfusion. The results obtained are as follows. (1) In response to perfusion with SM (200 μmol/L), the functional curve of carotid baroreflex was shifted to the right and upward with a decrease of peak slope (PS) and a reflex decrease in mean arterial pressure (RD)( P <0 01), indicating an inhibitory effect of SM on carotid sinus baroreflex. (2) By perfusing the isolated carotid sinus with high Ca 2+ solution (4 mmol/L), the inhibitory effect of SM on carotid baroreflex was partially eliminated. The functional curve of SM was shifted to the left and downward with PS increasing from 0 27±0 04 kPa to 0 37±0 02 kPa ( P <0 01) and RD was enhanced from 4 32±0 14 kPa to 6 18±0 17 kPa ( P <0 01). On the other hand, the threshold pressure (TP) and saturation pressure (SP) were significantly decreased from 10 29±0 29 kPa to 9 98±0 33 kPa ( P <0 05) and from 27 26±0 42 kPa to 25 22±0 38 kPa ( P <0 05), respectively. (3) By pretreatment with Bay K 8644 (500 nmol/L), an agonist of calcium channels, the effect of SM on carotid baroreflex was completely abolished. (4) Exposure of the carotid sinus to SM following pretreatment with charybdotoxin (ChTX,100 nmol/L), a blocker of the Ca 2+ activated K + channel (KCa), still inhibited the baroreflex. These results suggest that the inhibitory action of SM on carotid baroreflex may be mediated by suppressing Ca 2+ influx.[WT5HZ]

关 键 词：链霉素 颈动脉窦压力感受器反射 平均动脉压 窦内压 Ca^(2+)激活性K^(+)通道 

分 类 号：R965[医药卫生—药理学]