刺激蓝斑对心肌收缩力及肾交感神经放电的影响

在64只麻醉及人工呼吸的猫,观察到电刺激蓝斑(LC)能引起血压升高、心率加快,左心室收缩压升高,左心室内压最大变化率增加及肾交感神经放电(RNA)显著地增加。去缓冲神经对电刺激 LC 所引起的上述指标的增加幅度无明显影响,但可明显延长血压反应升高相以及血压恢复期的时间。LC 内微量注射谷氨酸钠可使血压下降,心率减慢,左室收缩压和左室内压最大变化率亦降低。LC 内注射海人酸,也能引起减压反应。而注射海人酸3h 后,使LC 神经元发生变性或去极化阻断时,再电刺激 LC 仍能引起明显的升压反应。以上结果表明,电刺激 LC 可使血压升高、心肌收缩力及肾交感神经放电增加,而 LC 内微量注射胞体兴奋剂则可降低血压、心率及心肌收缩力,说明电刺激 LC 引起的加压反应可能主要是兴奋了过路纤维所致,而 LC 本身神经元的兴奋引起的是减压反应。

EFFECTS OF STIMULATION OF LOCUS COERULEUS ON CARDIAC CONTRACTILITY AND RENAL NERVE ACTIVITY

Experiments were performed on 64 cats anesthetized with chloralose-urethane,paralyzed and artificially ventilated.Electrical stimulation of locus coeruleus(LC)elicited increases in BP,HR,LVSP,dP/dt max and RNA.Buffer nervesection had no effect on the increase of these parameters,but could prolong the timeof rise of BP and recovery phases.Injection of L-glutamate into LC,on the otherhand,could decrease BP,HR,LVSP and dP/dt max.Intra-LC injection of kainicacid could also decrease BP.When the LC neurons showed degeneration or de-polarization block after kainic acid injection,electrical stimulation of the LC couldstill elicit marked pressor response.The results suggest that the pressor responseinduced by electrical stimulation of LC might be mediated by the fibers passingthrough LC,while activation of LC neurons themselves would result in the depres-sor response.