Yao S T, Finkelstein D I, Lawrence A J
Department of Pharmacology, Monash University, Clayton, Victoria, Australia.
Neuroscience. 1999;91(2):621-9. doi: 10.1016/s0306-4522(98)00661-7.
To investigate whether nitric oxide is involved in the cardiovascular responses mediated via the locus coeruleus, the effects of microinjections of L-arginine and L-glutamate into the locus coeruleus on blood pressure and heart rate were investigated in sodium pentobarbitone-anaesthetized rats. Unilateral microinjection of L-arginine (25, 50 nmol) elicited dose-related depressor (-17 +/- 4, -25 +/- 4 mmHg) and bradycardic (13 +/- 3, 24 +/- 6 b.p.m.) effects. Furthermore, these effects were attenuated by prior local microinjection of N(G)-nitro-L-arginine (40 nmol). Peripheral muscarinic receptor blockade with atropine methyl nitrate (1 mg/kg, i.v.) attenuated the bradycardic but not the depressor responses to L-arginine. L-Glutamate (2 nmol) microinjections also mediated depressor (-27 +/- 6 mmHg) and bradycardic (53 +/- 23 b.p.m.) effects that were attenuated by microinjections of dizocilpine maleate (1 nmol) into the locus coeruleus. In addition, pretreatment with N(G)-nitro-L-arginine (40 nmol) also significantly attenuated the depressor response elicited by L-glutamate. These results suggest that nitrergic and glutamatergic pathways are operative within the locus coeruleus to modulate cardiovascular function, and also that a functional interaction may exist between the nitrergic and glutamatergic systems within the rat locus coeruleus.
为了研究一氧化氮是否参与经由蓝斑介导的心血管反应，在戊巴比妥钠麻醉的大鼠中，研究了向蓝斑微量注射L-精氨酸和L-谷氨酸对血压和心率的影响。单侧微量注射L-精氨酸（25、50 nmol）引起剂量相关的降压作用（-17±4、-25±4 mmHg）和心动过缓（13±3、24±6次/分钟）。此外，预先局部微量注射N(G)-硝基-L-精氨酸（40 nmol）可减弱这些作用。静脉注射硝酸甲基阿托品（1 mg/kg）进行外周毒蕈碱受体阻断可减弱对L-精氨酸的心动过缓反应，但不能减弱降压反应。微量注射L-谷氨酸（2 nmol）也介导降压作用（-27±6 mmHg）和心动过缓（53±23次/分钟），向蓝斑微量注射马来酸氯氮平（1 nmol）可减弱这些作用。此外，用N(G)-硝基-L-精氨酸（40 nmol）预处理也可显著减弱L-谷氨酸引起的降压反应。这些结果表明，蓝斑内的一氧化氮能和谷氨酸能通路在调节心血管功能中起作用，并且大鼠蓝斑内的一氧化氮能和谷氨酸能系统之间可能存在功能相互作用。
