Iturriaga R, Larraín C, Zapata P
Laboratory of Neurobiology, Catholic University of Chile, Santiago.
Brain Res. 1994 Nov 7;663(1):145-54. doi: 10.1016/0006-8993(94)90472-3.
The effects of domperidone, antagonist of D2 receptors, on arterial chemoreceptor activity were studied in spontaneously breathing and pentobarbitone anesthetized cats, in which recordings of chemosensory impulse activity were obtained simultaneously from both cut carotid (sinus) nerves. Intravenous injections of domperidone 50 micrograms/kg produced a maintained increase in the basal frequency of chemosensory discharges, after which hyperoxic tests (breathing 100% O2 for 30 s) evoked larger falls in the rate of chemosensory impulses. Chemosensory responses evoked by hypoxic hypoxia (100% N2 tests) and by cytotoxic hypoxia (i.v. injections of NaCN) reached higher impulse rates after domperidone treatment. The effects of domperidone reveal that a resting release of dopamine from glomus cells maintains a low level of basal chemosensory activity under normoxic conditions. Domperidone turns off such restraining dopaminergic control and enhances the transient chemosensory responses to hypoxic stimuli. Present data support a modulatory role for dopamine within the chemoreceptor process, but not its participation as excitatory transmitter between glomus cells and sensory nerve endings.
在自主呼吸和戊巴比妥麻醉的猫中研究了D2受体拮抗剂多潘立酮对动脉化学感受器活动的影响，在这些猫中，同时从双侧切断的颈动脉（窦）神经记录化学感受性冲动活动。静脉注射50微克/千克多潘立酮可使化学感受性放电的基础频率持续增加，在此之后，高氧试验（呼吸100%氧气30秒）引起化学感受性冲动频率更大幅度的下降。多潘立酮治疗后，低氧性缺氧（100%氮气试验）和细胞毒性缺氧（静脉注射NaCN）诱发的化学感受性反应达到更高的冲动频率。多潘立酮的作用表明，在常氧条件下，球细胞中多巴胺的静息释放维持了低水平的基础化学感受性活动。多潘立酮解除了这种抑制性多巴胺能控制，并增强了对低氧刺激的短暂化学感受性反应。目前的数据支持多巴胺在化学感受器过程中的调节作用，但不支持其作为球细胞和感觉神经末梢之间的兴奋性递质参与其中。
