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目的观察一氧化氮(nitric oxide,NO)在心血管中枢孤束核(NTS)和头端延髓腹外侧区(RVLM)内的心血管作用特点,从而明确其在介导中枢心血管功能调控中的意义。方法采用微量注射的方法观察麻醉SD大鼠NTS和RVLM增加或降低NO后动物血压、心率和肾交感神经活动的变化。结果在麻醉SD大鼠模型上,在心血管反射传入的中继站NTS内微量注射NO前体L-精氨酸(L-Arg,2nmol/50nl)能降低基础血压、心率和肾交感神经活动(P<0.05),而注射NO合酶(NOS)抑制剂NG-硝基-L-精氨酸甲酯(L-NAME,10nmol/50nl)能增加心血管功能(P<0.05)。在交感输出的关键区域RVLM注射L-Arg(2nmol/100nl)能增加血压、心率和交感神经活动(P<0.05),而给予L-NAME(10nmol/100nl)则抑制心血管功能(P<0.05)。结论 NO在不同的心血管中枢中具有不同的作用,提示其多样性效应对维持基础心血管功能具有特定的意义。
Objective To investigate the cardiovascular effects of nitric oxide (NO) in the central nucleus tractus of the cardiovascular system (NTS) and the rostral ventrolateral medulla (RVLM) in order to clarify its role in mediating central cardiovascular function significance. Methods The changes of blood pressure, heart rate and renal sympathetic nerve activity were observed by microinjection of NTS and RVLM in anesthetized SD rats. Results Microinjection of NO precursor L-arginine (L-Arg, 2 nmol / 50 nl) into the NTS of the cardiovascular reflex in anesthetized SD rats reduced basal blood pressure, heart rate and renal sympathetic nerve activity (P <0.05). However, injection of L-NAME (10nmol / 50nl), a NO synthase inhibitor, increased cardiovascular function (P <0.05). Injection of L-Arg (2 nmol / 100 nl) into RVLM in key areas of sympathetic output increased blood pressure, heart rate and sympathetic activity (P <0.05), while L-NAME (10 nmol / ). Conclusions NO plays different roles in different cardiovascular centers, suggesting that the diversity effect has particular significance in maintaining basic cardiovascular function.