家兔延髓腹外侧区内注射荷包牡丹碱对安定降低心脏功能的影响

INFLUENCE OF MICROINJECTION OF BICUCULLINE INTO VENTROLATERAL MEDULLA ON THE SUPPRESSION OF CARDIAC FUNCTION INDUCED BY DIAZEPAM IN RABBITS

家兔48只,用乌拉坦(1g/kg)静脉麻醉,三碘季铵酚制动,在人工呼吸下进行实验。静脉注射安定(0.5mg/kg)以及侧脑室注射氟安定(2mg溶于50μl人工脑脊液中)或γ-氨基丁酸(GABA)(300μg溶于50μl人工脑脊液中)都可降低心室内压峰值(PLVP),减少心力环面积(ACFL)和心室内压最大上升速率(dp/dt_(max))。安定和氟安定对PLVP、ACFL和dp/dt_(max)的抑制作用可被预先在侧脑室注射GABA受体拮抗剂印防己毒素(15μg溶于50μl人工脑脊液中)或双侧延髓腹外侧头端区(γVLM)微量注射GABA受体拮抗剂荷包牡丹碱(3μg溶于0.5μl生理盐水)所阻断。而在延髓网状巨细胞核中间部、网状小细胞核、孤束核或面神经核内注射同样剂量的荷包牡丹碱则不能阻断。 这些结果提示:延髓腹侧部GABA受体的激活可抑制心脏功能,安定对心脏功能的抑制作用可能通过激活延髓腹侧区GABA受体而实现。

Experiments were carried out on 48 rabbits anaesthetized with urethane (1 g / kg). The animals were immobilized with gallamine triethiodide and ventilated artificially. Both intravenous injection of diazepam (0.5 mg/kg) and intracerebroventricular injection of flurazepam (2 mg in 50μl) or gamma-aminobutyric acid (GABA) (300μg in 50μl) decreased the peak value of left ventricular pressure area of cardiac force loop and dp/ dt_(max). These suppressive effects of diazepam and flurazepam were prevented by intracerebroventricular injection of picrotoxin (15μg in 50μl) or microinjection of bicuculline(3μg in 0.5μl) into bilateral rostral ventrolateral medulla (γVLM). The results suggest that the inhibitory effects of diazepam on cardiac function may be mediated by activation of GABA receptor in γVLM.