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EFFECTS OF L-NNA AND NO DONORS ON SPONTANEOUS ACTIVITY OF ROSTRAL VENTROLATERAL MEDULLA NEURONS

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

(Department of Physiology, Institute of Bxsie Medicine, Hebei Medical University, Shijiazhuarag 050017)

Abstract

The effects of intravenous injection of a NO synthase inhibitor—N- nitro- Larginine (L- NNA)and NO donors—sodium nitroprusside (SNP)and SIN- I on
blood pressure (BP)，heart rate (HR) and spontaneous activity of rostral ventrolateral medulla (RVLM) neurons were examined in 22 anesthetized rats to define the action site of L-arginine:NO pathway in BP regulation. The results obtained were as follows. (1)Following i. v. injection of L-NNA，mean artery pressure (MAP)，HR and spontaneous discharge rate of 14 RVLM neurons were all increased，all effects starting at 5min after administration of L-NNA and lasting for more than 30 min. (2) In response to i. v. injection of SNP，MAP was decreased with concomitant increase in HR and the discharge rate of 23 RVLM neurons decreased in a dose-dependent manner. These effects were rapid in onset and also disappeared promptly. To exclude the effect of cerebral ischemia induced by decreased of BP，the effects of intracarotid injection of SNP were examined. Following i. a. injection，MAP was only slightly decreased and HR showed no significant change，but the discharge rate of 1 4 RVLM neurons was signify cantly decreased.(3)During i. v. injection of another NO donor—SIN一I，MAP and the spontaneous discharge rate of I 1 RVLM neurons were decreased. The above results indicate that the L-arginine:NO pathway may exert a modulatory action on the blood pressure through rostral ventrolateral medulla.

Key words: Rostral ventrolateral medulla;N-nitro-L-arginine; SIN-I;cardiovascular regulation ;;

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Citing This Article：

YANG LI-MING , HE RUI-RONG (HO SHIU-YONG. EFFECTS OF L-NNA AND NO DONORS ON SPONTANEOUS ACTIVITY OF ROSTRAL VENTROLATERAL MEDULLA NEURONS. Acta Physiol Sin 1996; 48 (4): (in Chinese with English abstract).