腺苷易化大鼠颈动脉窦压力感受器的活动

在36只麻醉大鼠,以隔离灌流颈动脉窦区记录窦神经传入放电的方法观察了腺苷（adenosine,Ado）对颈动脉窦压力感受器传入放电的影响。所得结果如下：（1）以75μmol／LAdo隔离灌流大鼠左侧颈动脉窦区时,窦内压-窦神经传入放电积分（ISP－ISNA）关系曲线向左上方移位,曲线最大斜率（PS）由（18．75±0．12）％／kPa增至（22．21±0．11）％／kPa（P＜0．001）,最大积分值（PIV）由（209．83±2．57）％增至（239．17±1．75）％;阈压（TP）和饱和压（SP）则分别从（8．57±0．24）和（22．99±0．34）下降至（7．15±0．23）kPa（P＜0．001）和（21．21±0,43）kPa（P＜0．01）。再分别以125和175μmol／LAdo灌流,机能曲线进一步向左上方移位,PS、TP和SP的变化均呈明显的剂量依赖性。（2）用腺苷选择性A1受体拮抗剂8－cyclopentyl－1,3－dipropylxanthine（0．134mmol／L）预处理后,Ado的上述效应即被阻断。（3）先给予KATP通道阻断剂格列苯脲（10μmol／L）亦可取消腔苷对窦神经传入放电的影响。结果表明,在体隔离灌流大鼠颈动脉窦区条件下,Ado对颈动脉窦压力感受器活动有易化作用,此作用似与腺苷A1受体介导的KATP通道开放有关。

Adenosine facilitates carotid baroreceptor activity in rats

The effects of adenosine (Ado) on the carotid baroreceptor were studied in 36 anesthetized rats with isolated carotid sinus perfusion by recording the sinus nerve afferent activity. The results obtained were as follows: (1) By perfusing the isolated carotid sinus with 75 mumol/L Ado, the functional curve for intrasinus pressure(ISP)-integral of sinus nerve activity (ISNA) relation was shifted to the left and upward with peak slope (PS) increased from (18.75 +/- 0.12)%/kPa to (22.21 +/- 0.11)%/kPa (P < 0.001) and the peak integral value (PIV) enhanced from (209.83 +/- 2.57)% to (239.17 +/- 1.75)% (P < 0.001), while the threshold pressure (TP) and saturation pressure (SP) were significantly decreased from 8.57 +/- 0.24 to 7.15 +/- 0.23 kPa (P < 0.001) and from 22.99 +/- 0.34 to 21.21 +/- 0.43 kPa (P < 0.01). By perfusing with high concentrations of Ado (125 and 175 mumol/L), the curves for ISP-ISNA relation were shifted to the left and upward further and the changes of the functional parameters such as PS, TP and SP were dose-dependent. (2) By pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (0.134 mmol/L), a selective adenosine A1-receptor antagonist, the above mentioned effects of Ado on carotid baroreceptor activity were abolished. (3) The Ado-induced increase in sinus nerve afferent activity could be eliminated by pretreatment with KATP channel blocker glibenclamide (10 mumol/L). The above results suggest that Ado exerts a facilitatory action on the isolated carotid baroreceptor and such an action of Ado may be attributed to the opening of KATP channels, which is mediated by A1-receptors.