Both NMDA and non-NMDA receptors in the NTS participate in the baroreceptor reflex in rats.
In this study, we determined whether either N-methyl-D-aspartate (NMDA) receptors or non-NMDA receptors in the nucleus tractus solitarii (NTS) participate in the baroreceptor reflex in rats. Microinjection of an NMDA receptor antagonist, MK-801, and a non-NMDA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione, into the NTS decreased the sensitivity of the baroreceptor reflex by 51 and 41%, respectively. Simultaneous administration of both agents further reduced the sensitivity of the baroreceptor reflex to 28% of control. A competitive NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid, also attenuated reflex bradycardia or tachycardia elicited by a single dose of phenylephrine or nitroprusside, respectively. Specificity of each antagonist's effects was supported by selective blockade of depressor responses produced by agonists that act at the NMDA and non-NMDA receptors, respectively. Results of this study indicate that both non-NMDA- and NMDA-sensitive receptors are involved in baroreceptor reflex transmission in the NTS.
Ohta
H
H
Department of Neurology, University of Iowa, Iowa City.
Talman
W T
WT
D015763:2-Amino-5-phosphonovalerate / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects*; D016291:Dizocilpine Maleate / Q000008:administration & dosage / Q000494:pharmacology*; D004347:Drug Interactions; D007839:Functional Laterality; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D011810:Quinoxalines / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology*
D011810:Quinoxalines; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C056723:FG 9041; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate