Avanzino G L, Ruggeri P, Blanchi D, Cogo C E, Ermirio R, Weaver L C
Istituto di Fisiologia Umana, Università degli Studi, Genoa, Italy.
Am J Physiol. 1994 May;266(5 Pt 2):H1722-8. doi: 10.1152/ajpheart.1994.266.5.H1722.
The cardiovascular effects of microinjections of two gamma-aminobutyric acid (GABA) antagonists specifically acting on GABAB receptors, 2-hydroxy-saclofen (2-OH-S) and CGP-35348, into vasopressor sites of rostral ventrolateral medulla (RVLM) were studied in rats anesthetized with urethan. Bilateral microinjection of 2-OH-S induced significant increases in mean arterial pressure (MAP) and heart rate (HR) in 21 of 26 RVLM vasopressor sites (81%); average increases obtained in the 26 sites studied were +25.2 +/- 3.0 mmHg and +12.7 +/- 2.1 beats/min. Bilateral microinjection of CGP-35348 induced significant increases in MAP and HR in 10 of 12 RVLM sites (83%). Average increases in the 12 sites studied were +27.6 +/- 3.9 mmHg and +14.6 +/- 2.5 beats/min. Sixteen rats received unilateral electrolytic lesions of one RVLM. Microinjections of either 2-OH-S or CGP-35348 into vasopressor sites within the intact RVLM significantly antagonized the depressor responses observed after injections of baclofen (20 pmol) into the same sites, whereas both GABAB antagonists did not affect the depressor response induced by microinjection of muscimol (5 pmol). These results suggest a tonic inhibitory mechanism within the RVLM mediated by GABAB receptors involved in central cardiovascular regulation.
在用乌拉坦麻醉的大鼠中，研究了向延髓头端腹外侧区（RVLM）的升压部位微量注射两种特异性作用于GABAB受体的γ-氨基丁酸（GABA）拮抗剂2-羟基-舒氯芬（2-OH-S）和CGP-35348的心血管效应。在26个RVLM升压部位中的21个（81%），双侧微量注射2-OH-S可显著升高平均动脉压（MAP）和心率（HR）；在所研究的26个部位中，平均升高分别为+25.2±3.0 mmHg和+12.7±2.1次/分钟。在12个RVLM部位中的10个（83%），双侧微量注射CGP-35348可显著升高MAP和HR。在所研究的12个部位中，平均升高分别为+27.6±3.9 mmHg和+14.6±2.5次/分钟。16只大鼠接受了一侧RVLM的单侧电解损伤。向完整RVLM内的升压部位微量注射2-OH-S或CGP-35348，可显著拮抗向同一部位注射巴氯芬（20 pmol）后观察到的降压反应，而两种GABAB拮抗剂均不影响微量注射蝇蕈醇（5 pmol）所诱导的降压反应。这些结果提示，RVLM内存在一种由GABAB受体介导的紧张性抑制机制，参与中枢心血管调节。
