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目的 研究一氧化氮 (NO)前体 L -精氨酸 (L - Arg)单侧微量注入大鼠延髓腹面加压区 (VSMp)对动脉血压 (AP)、心率 (HR)、肾灌流压 (PPk)的影响及与 L -谷氨酸 (L - Glu)升压作用的关系。 方法 采用延髓腹外侧部微量注射法 ,以整体灌流肾为模型观察与 NO有关药物对心血管活动的影响。 结果 (1) VSMp内微量注入L - Arg(4 0～ 10 0 nmol) ,AP和 HR呈剂量依赖性下降 ,与生理盐水注入后的变化相比较 ,差异均有显著性。如预先注入 NO合酶抑制剂 L -硝基 -精氨酸甲酯 (L - NAME)或鸟苷酸环化酶抑制剂甲基蓝 ,L - Arg的降压效应被衰减。(2 ) VSMp内微量注入 L - Arg(10 0 nmol) ,PPk与 AP同步下降 ,与基础值比较 ,差异有显著性。 (3) VSMp内微量注入 L - Glu(35 0 nm ol) ,AP上升。如预先注入 L - Arg(4 0～ 10 0 nmol)后 5 m in再注入 L - Glu,L - Glu的升压效应被衰减 ,衰减程度与 L - Arg呈剂量依赖性关系。 结论 VSMp内的 L - Arg- NO通路参与动脉血压的调控 ,其机制之一可能是通过抑制 VSMp内的谷氨酸能神经突触。
Objective To investigate the effect of unilateral injection of L - arginine (L - Arginine) into the rostral ventrolateral medulla (VSMp) on arterial blood pressure (AP), heart rate (HR) PPk) and its relationship with the increase of L - glutamic acid (L - Glu). Methods The medulla oblongata microinjection method was used to observe the effects of NO-related drugs on cardiovascular activity by perfusion of kidney. Results (1) Microinjection of L - Arg (40 ~ 100 nmol) into VSMp showed a dose - dependent decrease in AP and HR, and the difference was significant compared with saline injection. The antihypertensive effect of L - Arg was attenuated by pretreatment with L - nitro - arginine methyl ester (L - NAME) or guanylate cyclase inhibitor methyl blue. (2) Microinjection of L - Arg (100 nmol) into VSMp resulted in the simultaneous decrease of PPk and AP, which was significantly different from the baseline values. (3) Microinjection of L - Glu (35 0 nm ol) into VSMp increased AP. After pretreatment with L - Arg (4 0 ~ 100 nmol) and injecting L - Glu 5 min into L - Arg, the pressure increasing effect of L - Glu was attenuated. The degree of decay was in a dose - dependent manner with L - Arg. Conclusion L - Arg - NO pathway in VSMp is involved in the regulation of arterial blood pressure. One of the mechanisms may be through inhibition of glutamatergic synapses in VSMp.