大鼠延髓腹面降压区微量注射L-精氨酸对心血管活动的影响

EFFECTS OF MICROINJECTION OF L ARGININE INTO THE DEPRESSOR AREA OF VENTRAL SURFACE OF MEDULLA OBLONGATA ON CARDIOVASCULAR RESPONSES

目的 :观察NO前体L 精氨酸 (L Arg)微量注入大鼠延髓腹面降压区 (VSMd)对心血管活动的影响及其和L 谷氨酸 (L Glu)降压作用的关系。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有关的药物对心血管活动的影响。结果 :①VSMd内微量注入L Arg ,动脉血压 (AP)呈剂量依赖性升高 ,肾灌流压 (PPK)与AP同步上升 ,与注入生理盐水对照 ,差异均具有显著意义 ,但L Arg对心率无显著影响 ;②预先在VSMd内注入甲基蓝可取消L Arg的升压、升PPK作用 ;③VSMd内注入L Glu ,AP下降。如预先注入L Arg后 5min再注入L Glu ,L Glu的降压效应被衰减 ,其衰减程度依赖于L Arg剂量。 结论 :VSMd内的L Arg NO通路参与延髓心血管中枢对AP的调控 。

Aim:To study the effects of L arginine,a precursor for the synthesis of nitric oxide,when it was microinjected into the functio nally identified depressor area in ventral surface of medulla oblongata (VSMd) on cardiovascular responses.Methods:Artery pressure (AP),perfusion pressure of the kidney (PPK) and heart rate were recorded to study the effects of microinjection of NO related drugs into VSMd.Results:①Unilateral microinjection of L arginine (60～100 nmol) into VSMd produced prominent dose related pressor effect and increased PPK but without significant changes in heart rate.②Microinjection of L Arg (100 nmol) 3 min after microinjection of methylene blue (10 nmol) into VSMd did not significantly change AP and PPK.③Unilateral microinjection L glutamate (350 nmol) into VSMd elicited depressor effect (-34.97%±4.33%).The depressor effect was significantly dosed related attenuated by prior microinjection L arginine (60～100 nmol) into the same area.Conclusion: These results suggest that the L arginine -NO pathway in the VSMd participate in the central regulation of artery pressure and the pathway may have a key role in inhibiting glutamatergic neurotransmission in the anesthetized rats.