微量注射L—精氨酸及L—NMMA至延髓头端腹外侧区对血压,心率的影响

微量注射一氧化氮（NO）前体L-精氨酸至用乌拉坦和氯醛糖混合麻醉的雄性SD大鼠的延髓头端腹外侧区（rVLM），可引起血压（BP）和心率（HR）的快速明显下降．电刺激中脑中央导水管周围灰质背侧部（dPAG）诱发的防御性升压反应受到明显抑制。相反，微量注射NO合成抑制剂L-NG-单甲基-L-精氨酸（L—NMMA）至rVLM，则引起BP和HR的快速明显升高，电刺激dPAG诱发的防御性升压反应明显增强。结果提示，NO参与rVLM神经元调节心血管活动的信息传递过程，并在其中起抑制性作用。

INFLUENCE OF MICROINJECTION OF L-ARGININE AND L-N~G-MONOMETHYL-L-ARGININE INTO THE ROSTRAL VENTROLATERAL MEDULLA ON BLOOD PRESSURE AND HEART RATE IN RATS

Microinjection of L--arginine, a precursor of nitric oxide (NO), into the rostral ventroalteralmedulla(rVLM), on male SD rats anesthetized with urethane and chloralase, caused a rapid decrease in bloodpressure (BP) and heart rate (HR), as well as the Pressor to stimulation of the dorsal Periaqueductalgrey (dPAG) in the midbrain. Whereas, microinjection of L--NG--monomethyl--L--arginine (L--NMMA), ablocker of the formation of NO, into the rVLM, caused a rapid increase in BP and HR, as well as the pressorresponse to stimulation of the dPAG. These results suggest that NO plays an inhibitory role in the messagetransmission of the cardiovascular regulation by the neurons in the rVLM.0.