Brainstem mechanisms controlling cardiovascular reflexes in channel catfish

Microinjections of kynurenic acid and kainic acid into the general visceral nucleus (nGV), homologous to the mammalian nucleus tractus solitarius of the medulla, in anesthestized, spontaneously breathing catfish were used to identify central areas and mechanisms controlling resting normoxic heart ra...

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Bibliographic Details
Published in:Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2014-04, Vol.170, p.1-5
Main Authors: Turesson, J., Hedrick, M.S., Sundin, L., Burleson, M.L.
Format: Article
Language:English
Subjects:
AMPA
Animals
blood pressure
Blood Pressure - drug effects
Brain Stem - physiology
Cardiovascular System
Central
Chemosensitivity
Chemosensitivity, Central
fish
Freshwater
general visceral nucleus
Heart rate
Heart Rate - drug effects
heart rate, blood pressure, general visceral nucleus, fish, hypoxia, kainic acid, kynurenic acid, kainic acid
hypoxia
Ictaluridae - physiology
Ictalurus punctatus
kainic acid
kynurenic acid
Kynurenic Acid - administration & dosage
Medulla Oblongata - drug effects
NMDA
Receptors
Receptors, Ionotropic Glutamate - antagonists & inhibitors
Receptors, Ionotropic Glutamate - metabolism
Receptors, NMDA, AMPA
Reflex - physiology
Respiration
Zoologi
Zoology
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Summary:Microinjections of kynurenic acid and kainic acid into the general visceral nucleus (nGV), homologous to the mammalian nucleus tractus solitarius of the medulla, in anesthestized, spontaneously breathing catfish were used to identify central areas and mechanisms controlling resting normoxic heart rate and blood pressure and the cardiovascular responses to hypoxia. Kynurenic acid, an antagonist of ionotropic glutamate receptors, significantly reduced resting normoxic heart rate but did not block the bradycardia associated with aquatic hypoxia. Kainic acid (an excitotoxic glutamatergic receptor agonist) also significantly reduced normoxic heart rate, but blocked the hypoxia-induced bradycardia. Neither kynurenic acid nor kainic acid microinjections affected blood pressure in normoxia or hypoxia. The results of this study indicate that glutamatergic receptors in the nGV are involved in the maintenance of resting heart rate and the destruction of these neurons with kainic acid abolishes the bradycardia associated with aquatic hypoxia.
ISSN:1095-6433
1531-4332
DOI:10.1016/j.cbpa.2014.01.003