Su X, Zhang W Y, Ho S Y
Department of Physiology, Hebei Medical College, Shijiazhuang.
Sheng Li Xue Bao. 1991 Jun;43(3):291-5.
The response of single carotid chemoreceptor afferent fibers upon adenosine acting on the carotid body (CB) was examined in 39 urethan-anesthetized rabbits. Totally 73 units with spontaneous discharge were recorded in our experiment. The results were as follows: (1) Of 55 units, 51 showed an increase in discharge frequency from 0.76 +/- 0.10 to 1.53 +/- 0.23 imp/s. A few new units were recruited concomitantly in response to intracarotid injection of adenosine (10 micrograms/kg). (2) Adding adenosine in the doses of 0.5, 1.5, 10, 50 and 100 micrograms/kg to the perfusate passing through the isolated carotid sinus led to dose-dependent increase in the discharge from 0.51 +/- 0.06 to 0.58 +/- 0.07, 0.78 +/- 0.13, 0.96 +/- 0.15, 1.11 +/- 0.17, 1.34 +/- 0.21 and 1.38 +/- 0.18 imp/s, respectively (P less than 0.001, n = 9 units). (3) In other 9 units with spontaneous discharge rate of 1.30 +/- 0.40 imp/s, the activity was decreased to 0.56 +/- 0.19 imp/s (P less than 0.01) by intracarotid injection of dopamine (50 micrograms/kg). Intracarotid injection of adenosine to the CB pretreated with dopamine still activated the units with an increase in firing rate to 1.07 +/- 0.28 imp/s (P less than 0.01). However, the increment was less prominent as compared with that of adenosine administration before dopamine injection (P less than 0.001). From the results obtained, it is hypothesized that the exciting effect of adenosine on the CB chemoreceptor may be attributed to its action on the presynaptic component of the chemoreceptor complex in attenuating the release of inhibitory transmitter dopamine, and its direct stimulating action on the chemosensory nerve endings.
在39只经乌拉坦麻醉的家兔中，研究了腺苷作用于颈动脉体（CB）时单个颈动脉化学感受器传入纤维的反应。实验中总共记录到73个有自发放电的单位。结果如下：（1）在55个单位中，51个单位的放电频率从0.76±0.10次/秒增加到1.53±0.23次/秒。颈内注射腺苷（10微克/千克）时，同时有少数新单位被募集。（2）向流经离体颈动脉窦的灌注液中添加0.5、1.5、10、50和100微克/千克剂量的腺苷，导致放电频率呈剂量依赖性增加，分别从0.51±0.06次/秒增加到0.58±0.07次/秒、0.78±0.13次/秒、0.96±0.15次/秒、1.11±0.17次/秒、1.34±0.21次/秒和1.38±0.18次/秒（P＜0.001，n = 9个单位）。（3）在另外9个自发放电频率为1.30±0.40次/秒的单位中，颈内注射多巴胺（50微克/千克）后，活动降至0.56±0.19次/秒（P＜0.01）。向用多巴胺预处理过的颈动脉体颈内注射腺苷仍能激活这些单位，放电频率增加到1.07±0.28次/秒（P＜0.01）。然而，与多巴胺注射前给予腺苷相比，增加幅度较小（P＜0.001）。从所得结果推测，腺苷对颈动脉体化学感受器的兴奋作用可能归因于其对化学感受器复合体突触前成分的作用，减弱抑制性递质多巴胺的释放，以及对化学感觉神经末梢的直接刺激作用。
