孤束核腺苷A1受体在右美托咪定增强大鼠压力反射敏感性中的作用

Role of adenosine A1 receptor within nucleus tractus solitarii in dexmedetomidine-induced increase in baroreflex sensitivity in rats

目的评价孤束核腺苷A1受体(A1AR)在右美托咪定增强大鼠压力反射敏感性(BRS)中的作用.方法清洁级健康雄性SD大鼠32只,体重240~280 g,采用随机数字表法分为4组(n=8):对照组(C组)、溶剂对照组(S组)、右美托咪定组(D组)和右美托咪定+8-环戊基-1,3-二丙基黄嘌呤(DPCPX,高选择性A1 AR拮抗剂)组(DD组).大鼠麻醉后,通过脑立体定向仪将1μl药液注射至右侧孤束核.C组和D组注射生理盐水,S组注射二甲基亚砜,DD组注射DPCPX.股静脉置管后,D组和DD组经15 min静脉输注右美托咪定100μg/kg,随后以50μg·kg^-1·h^-1输注105 min.C组和S组输注等量生理盐水.于静脉输注前即刻、输注开始后60和120 min(T0-2)时采用去氧肾上腺素升压法测定BRS.结果与C组和S组比较,D组和DD组T1,2时BRS升高(P<0.05);与D组比较,DD组T1,2时BRS降低(P<0.05).结论 A1 AR参与了右美托咪定增强大鼠BRS的过程.

Objective To evaluate the role of A1 adenosine receptor ( A1 AR) within the nucleus tractus solitarii ( NTS ) in dexmedetomidine-induced increase in baroreflex sensitivity ( BRS ) in rats. Methods Thirty-two clean-grade healthy male Sprague-Dawley rats, weighing 240-280 g, were divided in-to 4 groups ( n=8 each) using a random number table method: control group ( group C), solvent control group ( group S), dexmedetomidine group ( group D), and dexmedetomidine plus 8-cyclopentyl-1,3-diprop-ylxanthine (DPCPX, a highly selective A1AR blocker) group (group DD). After the rats were anesthe-tized, 1 μl drug liquid was injected into the right NTS with a brain stereotaxic apparatus. Oneμl normal sa-line was injected into the right NTS in C and D groups, 1 μl dimethyl sulfoxide in group S, and 1 μl DPCPX in group DD. After catheters were implanted into the femoral vein, dexmedetomidine was intrave-nously infused as a bolus of 100μg/kg over 15 min followed by an infusion of 50μg·kg^-1 ·h^-1 for 105 min in D and DD groups. The equal volume of normal saline was given instead of dexmedetomidine in C and S groups. BRS was measured using phenylephrine immediately before intravenous infusion (T0) and at 60 and 120 min after beginning of infusion ( T1,2 ). Results Compared with C and S groups, the BRS was signifi-cantly increased at T1,2 in D and DD groups ( P<0. 05). Compared with group D, the BRS was significantly decreased at T1,2 in group DD ( P<0. 05). Conclusion A1 AR within the NTS is involved in dexmedetomi-dine-induced increase in BRS in rats.