title: Excitatory amino acid receptors in the dorsomedial hypothalamic area contribute to the chemoreflex tachypneic response.
abstract: This study evaluated the effect of blockade of the excitatory amino acid (EAA) receptors in the dorsomedial hypothalamic (DMH) area on the ventilatory and cardiovascular responses of the chemoreflex activation in conscious rats. Bilateral microinjection of kynurenic acid (2.7 nmol, n = 6) into the DMH area reduced the tachypneic (+ 264 ± 13 versus + 204 ± 14 cpm, P < 0.05) and pressor (+ 52 ± 5 versus + 31 ± 6 mmHg, P < 0.05) components of chemoreflex but had no effect on the bradycardic component (-214 ± 7 versus -244 ± 17 bpm) of the chemoreflex. The magnitudes of the reduction in pressor and tachypneic chemoreflex responses were not significantly correlated (r = 0.308, P = 0.330). These data indicate that neurons located in the DMH area are activated by chemoreflex; that this activation is mediated via EAA receptors; and that it is essential for the full expression of the respiratory component of the chemoreflex.
authors: Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Nathália T
authors: NT
authors: Silva
authors: School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia.
authors: Eugene
authors: E
authors: Nalivaiko
authors: Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Luiz G
authors: LG
authors: da Silva
authors: Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address: haibara@icb.ufmg.br.
authors: Andréa S
authors: AS
authors: Haibara
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007736:Kynurenic Acid / Q000494:pharmacology; D008297:Male; D010991:Plethysmography; D011190:Potassium Cyanide / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000378:metabolism*; D012119:Respiration / Q000187:drug effects; D059246:Tachypnea / Q000139:chemically induced / Q000378:metabolism*; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D007736:Kynurenic Acid; D011190:Potassium Cyanide
keywords: Chemoreflex; Dorsomedial hypothalamus; Excitatory amino acid receptor; Tachypneic response