Glutamatergic and purinergic mechanisms on respiratory modulation in the caudal NTS of awake rats.
In the present study we evaluated the role of ionotropic glutamate receptors and purinergic P2 receptors in the caudal commissural NTS (cNTS) on the modulation of the baseline respiratory frequency (fR), and on the tachypneic response to chemoreflex activation in awake rats. The selective antagonism of ionotropic glutamate receptors with kynurenic acid (2 nmol/50 nl) in the cNTS produced a significant increase in the baseline fR but no changes in the tachypneic response to chemoreflex activation. The selective antagonism of purinergic P2 receptors by PPADS (0.25 nmol/50 nl) in the cNTS produced no changes in the baseline fR or in the tachypneic response to chemoreflex activation. The data indicate that glutamate acting on ionotropic receptors in the cNTS plays a inhibitory role on the modulation of the baseline fR but had no effect on the tachypneic response to chemoreflex activation, while ATP acting on P2 receptors in the cNTS plays no major role in the modulation of the baseline fR or in the tachypneic response to chemoreflex activation. We suggest that neurotransmitters other than l-glutamate and ATP are involved in the processing of the tachypneic response of the chemoreflex at the cNTS level.
Braccialli
Alex L
AL
Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes 3900, 14049-900 Ribeirão Preto, SP, Brazil.
Bonagamba
Leni G H
LG
Machado
Benedito H
BH
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007736:Kynurenic Acid / Q000494:pharmacology; D008297:Male; D008845:Microinjections / Q000379:methods; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D010991:Plethysmography / Q000379:methods; D011687:Purines / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration / Q000187:drug effects; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D010975:Platelet Aggregation Inhibitors; D011687:Purines; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D018698:Glutamic Acid; D011732:Pyridoxal Phosphate; D007736:Kynurenic Acid; C030985:purine