Electrophysiological evidences for the contribution of NMDA receptors to the inhibition of clonidine on the RVLM presympathetic neurons.
The main objective of this study is to test the hypothesis that N-methyl-D-aspartate (NMDA) receptors within the rostral ventrolateral medulla (RVLM) are involved in the inhibition of clonidine on the RVLM presympathetic neurons. Totally, 22 presympathetic neurons were recorded in anesthetized and paralyzed rats. The majority of these neurons (n=16 of 22) were significantly inhibited by iontophoretic (30 nA) clonidine, the other 6 neurons were insensitive to clonidine. In seven clonidine-sensitive neurons, iontophoretic clonidine (30 nA) antagonized the neuronal excitation of iontophoretic NMDA receptor agonist NMDA (20 nA). In remaining nine clonidine-sensitive neurons, iontophoretic NMDA receptor antagonist MK801 (60 nA) significantly attenuated the neuronal inhibition of iontophoretic (30 nA) clonidine. In conclusion, these results suggest that NMDA receptors contribute to the inhibition of clonidine on the RVLM presympathetic neurons.
Wang
Wei-Zhong
WZ
Department of Physiology, Second Military Medical University, 800 Xiang-Yin Road, Shanghai 200433, China. wangwz68@hotmail.com
Yuan
Wen-Jun
WJ
Tang
Chao-Shu
CS
Su
Ding-Feng
DF
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004594:Electrophysiology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects* / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D003000:Clonidine