Kihara M, Kubo T
Department of Pharmacology, Yokohama City University School of Medicine, Japan.
Arch Int Pharmacodyn Ther. 1988 Sep-Oct;295:67-79.
Drugs activating GABAergic systems were microinjected into the caudal ventrolateral medulla of the rat and effects on blood pressure and heart rate were investigated. In urethane-anesthetized rats, a dose-dependent increase in blood pressure and heart rate was induced by unilateral injections of GABA (30-300 ng) into the caudal ventrolateral medulla. Unilateral injections of the GABA receptor agonist muscimol (1-10 ng) and baclofen (0.1-10 ng) into the brainstem area also increased both the cardiovascular parameters. The GABA uptake inhibitors nipecotic acid (1-3 micrograms) and L-2,4-diaminobutyric acid (1 microgram), and the GABA-T inhibitor gamma-acetylenic GABA (1-3 micrograms) injected unilaterally into the brainstem area also produced hypertension and tachycardia. Bilateral microinjections of nipecotic acid (0.3 microgram) into the area potentiated the pressor and tachycardiac responses to carotid artery occlusion in pentobarbital-anesthetized rats. Lesioning of the rat nucleus tractus solitarii did not alter the GABA content in the lesioned side of the caudal ventrolateral medulla. The data provide further evidence that endogenous GABAergic mechanisms in the rat caudal ventrolateral medulla are involved in the regulation of blood pressure. It seems unlikely that the GABAergic mechanisms originate mainly from neurons in the nucleus tractus solitarii.
将激活γ-氨基丁酸（GABA）能系统的药物微量注射到大鼠延髓尾端腹外侧，研究其对血压和心率的影响。在氨基甲酸乙酯麻醉的大鼠中，向延髓尾端腹外侧单侧注射GABA（30 - 300纳克）可引起血压和心率呈剂量依赖性升高。向脑干区域单侧注射GABA受体激动剂蝇蕈醇（1 - 10纳克）和巴氯芬（0.1 - 10纳克）也会使这两种心血管参数升高。向脑干区域单侧注射GABA摄取抑制剂尼克酸（1 - 3微克）和L - 2,4 - 二氨基丁酸（1微克）以及GABA - T抑制剂γ - 乙炔基GABA（1 - 3微克）也会导致高血压和心动过速。向该区域双侧微量注射尼克酸（0.3微克）可增强戊巴比妥麻醉大鼠对颈动脉闭塞的升压和心动过速反应。损毁大鼠孤束核不会改变延髓尾端腹外侧损毁侧的GABA含量。这些数据进一步证明大鼠延髓尾端腹外侧的内源性GABA能机制参与血压调节。GABA能机制似乎不太可能主要起源于孤束核中的神经元。
