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EFFECTS OF MICROINJECTION OF L-NNA AND SNP INTO VENTROLATERAL MEDULLA ON BLOOD PRESSURE HEART RATE AND RENAL SYMPATHETIC NERVE ACTIVITY IN RATS，

YANG LI-MING , HE RUI-RONG (HO SHIU-YONG)

(Department of Physiology，Institute of Basic Medicine, Hebei Medical University,Hebei Shijiazhuang 050017)

Abstract

The effects of microinjection of a NO synthase inhibitor—N-nitro-L-arginine (L-NNA) and NO donor-sodium nitroprusside (SNP) into ventrolateral medulla on blood pressure (BP)，heart rate (HR) and renal sympathetic nerve activity (RSNA) were examined in anesthetized rats to define the role of L-arginine:NO pathway in the central regulation of BP and to explore the underlying mechanism. The results obtained were as follows:(I)Following microinjection of L-NNA into rostral ventrolateral medulla (RVLM)，both of MAP and RSNA were increased. The effects lasted for more than 30 min and could be reversed by prior intravenous injection of L-arginine.(2)In response to microinjection of SNP into RVLM，MAP and RSNA were decreased，while HR showed no significant change. (3) During microinjection of L-NNA into caudal ventrolateral medulla (CVLM)，MAP，HR and RSNA were decreased.
(4)Upon injection of SNP into CVLM，MAP and RSNA were increased，but HR
showed no significant change. The above-mentioned results indicate that the L-arginine :NO pathway may exhibit a modulatory action on the activity of ventrolateral medulla neurons.

Key words: Rostral ventrolateral medulla;caudal ventrolateral medulla;N- nitro- L- arginine;sodium nitroprusside;L-arginine;;

Received: 　　Accepted:

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Citing This Article：

YANG LI-MING , HE RUI-RONG (HO SHIU-YONG). EFFECTS OF MICROINJECTION OF L-NNA AND SNP INTO VENTROLATERAL MEDULLA ON BLOOD PRESSURE HEART RATE AND RENAL SYMPATHETIC NERVE ACTIVITY IN RATS，. Acta Physiol Sin 1996; 48 (4): (in Chinese with English abstract).