高血压大鼠延髓头端腹外侧区GABA_B受体中介的心血管效应

Cardiovascular Effects Mediated by GABA_B Receptor in the Rostral Ventrolateral Medulla of Spontaneously Hypertensive Rats

目的 :证实自发性高血压大鼠延髓头端腹外侧区 ( RVL M) γ-氨基丁酸 ( GABA) B受体中介的紧张性抑制作用。方法 :于大鼠双侧 RVL M微量注射 2 -羟基 -saclofen,观察其平均动脉血压( MAP)和心率 ( HR)变化。结果 :在 SD、WKY、SHR大鼠均引起 MAP升高和 HR加快 ,但 SHR大鼠明显低于正常对照组的 SD、WKY大鼠 ( P<0 .0 5)。结论 :GABAB受体参与中介 RVL M的紧张性抑制作用 ,SHR大鼠 RVL M的此紧张性抑制作用明显低于正常血压大鼠。

Objective: To determine the role of γ aminobutyric acid (GABA) B receptor in mediating the tonic inhibitory influence on the rostral ventrolateral medulla (RVLM) in the spontaneously hypertensive rat. Methods:Bilateral microinjection of 2 hydroxy saclofen (2 OH S ) into RVLM was performed in urethane anaesthetized Sprague Dawley (SD), Wistar Kyoto (WKY) and spontaneously hypertensive (SH) rats, and arterial blood pressure (Bp) and heart rate (HR) were observed. Results: Blockade of the GABA B receptor by bilateral injection of 20 mmol/L of 20nl 2 OH S into RVLM resulted in increases in both Bp and HR. The increases in these haemodynamic parameters following the GABA B receptor blockade were significantly smaller in SH than those in normotensive SD and WKY rats ( P <0.05). Conclusion: GABA B receptor mediates the tonic inhibitory influence on RVLM, the inhibitory tonic influence mediated by GABA B receptor is smaller in SH rats.