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Excitatory amino acid receptors in the dorsomedial hypothalamus are not involved in the regulation of the tachypneic response induced by chemoreflex (686.34)
Author(s) -
Haibara Andrea,
Silva Nathália,
Nalivaiko Eugene
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.686.34
Subject(s) - kynurenic acid , microinjection , medicine , endocrinology , stimulation , excitatory postsynaptic potential , receptor , blockade , chemistry , chemoreceptor , control of respiration , baroreceptor , respiratory system , glutamate receptor , heart rate , blood pressure
EAA receptors into the DMH are involved in the control of sympathoexcitatory component of the chemoreflex, because kynurenic acid into DMH reduces the chemoreflex pressor response. Stimulation of the DMH elicited an increase in respiratory frequency. Considering that activation of inspiratory neurons on the ventral surface of the brainstem can increase the activity of sympathetic preganglionic neurons, we cannot rule out that the blockade of the DMH by kynurenic acid affects the chemoreflex ventilatory responses and consequently the pressor response. This study evaluated the effect of EAA receptors blockade in the DMH on the ventilatory and cardiovascular responses induced by intravenous injection of potassium cyanide (KCN) in conscious rats. Bilateral microinjection of kynurenic acid (2.7 nmol, n=6) into the DMH produced no significant changes on the tachypneic (+198±27 vs +163±19) and bradycardic responses (‐214±7 vs ‐244±17 bpm), but reduced the pressor response (+49±4 vs +23±11 mmHg) of the chemoreflex. Furthermore, the bilateral microinjection of kynurenic acid also produced no changes on baseline cardiovascular parameters (104±3 vs 105±3 mmHg; 330±5 vs 358±12 bpm) and baseline respiratory rate (129±12 vs 120±8 cpm). These results indicate that EAA receptors in the DMH are not involved in the tachypneic response of the chemoreflex, suggesting that the reduction on chemoreflex pressor response induced by kynurenic acid was not a consequence of reduction in respiratory activity. Grant Funding Source : Supported by INCT‐CNPq/ CAPES/ FAPEMIG