Evidence for the involvement of endogenous aspartate in the mediation of carotid chemoreceptor reflexes in the rostral ventrolateral medulla of the rat.
2-Amino-5-phosphonovalerate (AP5; 153 pmol) injected into the rostral ventrolateral medulla (RVLM) inhibited pressor responses induced by carotid chemoreceptor stimulation. AP5 also inhibited pressor responses to aspartate (0.75 nmol) but not to glutamate (0.53 nmol) similarly injected. High K+ (50 mM) released endogenous aspartate and glutamate in a Ca2+-dependent manner from the RVLM. Chemoreceptor stimulation caused a release of aspartate but not of glutamate in the RVLM, and sinus nerve denervation abolished the release of aspartate. Increases in blood pressure induced by intravenous phenylephrine did not release aspartate. These results support the hypothesis that endogenous aspartate in the rat RVLM is involved in the mediation of chemoreceptor reflexes.
Kubo
T
T
Department of Pharmacology, Showa College of Pharmaceutical Sciences, Machida, Tokyo, Japan.
Asari
T
T
Amano
M
M
Hagiwara
Y
Y
Fukumori
R
R
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002344:Carotid Body / Q000187:drug effects / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism*; D008845:Microinjections; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex; D013238:Stereotaxic Techniques
D018691:Excitatory Amino Acid Antagonists; D010656:Phenylephrine; D001224:Aspartic Acid; D018698:Glutamic Acid; D015763:2-Amino-5-phosphonovalerate; D011188:Potassium