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Study of glutamatergic and purinergic mechanisms involved on autonomic and respiratory modulation in ventrolateral medulla of rats

Grant number: 10/09805-3
Support type:Scholarships in Brazil - Doctorate (Direct)
Effective date (Start): October 01, 2010
Effective date (End): December 31, 2011
Field of knowledge:Biological Sciences - Physiology
Principal Investigator:Benedito Honorio Machado
Grantee:Davi José de Almeida Moraes
Home Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The activation of peripheral chemoreceptors, which detect reductions in partial pressure of arterial oxygen (PaO2), promotes, in awake rats, respiratory and cardiovascular adjustments aimed at normalize the PaO2 and blood perfusion pressure. As a consequence of activation of the chemoreflex, we observed an increase in blood pressure, tachypnea and a behavioral response. There is evidence that neurons generating of respiratory and sympathetic activity located in the ventrolateral medulla (approximately 600 ¼m of extension; VLM) are part of the neural pathways responsible for respiratory and cardiovascular responses to chemoreflex activation. Our previous results obtained in awake rats suggest the involvement of L-glutamate and ATP in the VLM in neurotransmission of cardiovascular and respiratory components to activation of the chemoreflex. Furthermore, studies in the literature suggest the involvement of the VLM, and the purinergic and glutamatergic neurotransmission in the genesis of sympathetic and respiratory changes resulting from exposure to Chronic Intermittent Hypoxia (CIH). However, the involvement of purinergic and glutamatergic transmission in different antero-posterior aspects of VLM on the cardiovascular and respiratory baseline parameters and chemoreflex responses, as well as on autonomic and ventilatory changes observed in experimental model of CIH, has not been clearly established in experimental models without anesthesia. The hypothesis of this project is as follows: the purinergic and glutamatergic neurotransmission play distinct roles in different anteroposterior aspects of VLM on the cardiovascular and respiratory baseline parameters and on chemoreflex responses. Furthermore, we consider also the hypothesis that after CIH changes occur in these purinergic and glutamatergic mechanisms in the VLM. (AU)