[Effects of L-NNA and NO donors on spontaneous activity of rostral ventrolateral medulla neurons].
The effects of intravenous injection of a NO synthase inhibitor--N-nitro-L-arginine (L-NNA) and NO donors--sodium nitroprusside (SNP) and SIN-1 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 5 min 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 14 RVLM neurons was significantly decreased. (3) During i.v. injection of another NO donor--SIN-I, MAP and the spontaneous discharge rate of 11 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.
Yang
L M
LM
Department of Physiology, Hebei Medical University, Shijiazhuang.
He
R R
RR
Ho
S Y
SY
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004594:Electrophysiology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D019335:Nitroarginine / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D009599:Nitroprusside; D010656:Phenylephrine; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase