Verberne A J, Guyenet P G
Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908.
Am J Physiol. 1992 Dec;263(6 Pt 2):R1195-202. doi: 10.1152/ajpregu.1992.263.6.R1195.
The central pathway mediating the Bezold-Jarisch reflex elicited by jugular vein injection of serotonin (5-HT) and phenyl biguanide (PBG) was studied in halothane-anesthetized, paralyzed rats. 5-HT and PBG produced hypotension and inhibition of lumbar sympathetic discharge often preceded by sympathoexcitation. The Bezold-Jarish reflex was blocked by bilateral kynurenic acid (KYN; glutamate antagonist, 1.25 nmol/side) microinjection into the solitary tract nucleus. Bilateral KYN injection into the caudal ventrolateral medulla (5 nmol/side) also blocked the reflex. Bilateral injection of bicuculline methiodide (BIC; 100 pmol/side) into the rostral ventrolateral medulla (RVL) reduced the depressor and sympathoinhibitory components of the reflex and enhanced an excitatory component. Blockade or attenuation of the Bezold-Jarisch reflex was always associated with a concomitant blockade or attenuation of the arterial baroreflex. RVL barosensitive neurons (n = 61) were inhibited (> 60% reduction in firing) by PBG and 5-HT. Iontophoretic application of BIC (n = 11 cells), but not strychnine (glycine antagonist), blocked inhibition of RVL neurons by 5-HT and PBG. The sympathoinhibitory component of the Bezold-Jarisch reflex may use a central pathway similar to that of the arterial baroreflex.
在氟烷麻醉、麻痹的大鼠中，研究了经颈静脉注射5-羟色胺（5-HT）和苯基双胍（PBG）引发贝佐尔德-贾里什反射的中枢通路。5-HT和PBG可导致低血压，并抑制腰交感神经放电，且常常先出现交感神经兴奋。双侧向孤束核微量注射犬尿氨酸（KYN；谷氨酸拮抗剂，每侧1.25 nmol）可阻断贝佐尔德-贾里什反射。双侧向尾侧腹外侧延髓注射KYN（每侧5 nmol）也可阻断该反射。双侧向头侧腹外侧延髓（RVL）注射甲磺酸荷包牡丹碱（BIC；每侧100 pmol）可减弱该反射的降压和交感抑制成分，并增强其兴奋成分。贝佐尔德-贾里什反射的阻断或减弱总是与动脉压力反射的同时阻断或减弱相关。PBG和5-HT可抑制RVL压力敏感神经元（n = 61）（放电减少>60%）。离子电泳施加BIC（n = 11个细胞）可阻断5-HT和PBG对RVL神经元的抑制作用，但施加士的宁（甘氨酸拮抗剂）则无此作用。贝佐尔德-贾里什反射的交感抑制成分可能使用了与动脉压力反射类似的中枢通路。
