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Effect of sympathetic activation on blood flow within the carotid body of normo- and hypertensive rats

Grant number: 21/15149-6
Support Opportunities:Scholarships abroad - Research Internship - Doctorate
Start date: July 15, 2022
End date: June 30, 2023
Field of knowledge:Biological Sciences - Physiology - Physiology of Organs and Systems
Principal Investigator:Davi José de Almeida Moraes
Grantee:Karolyne Silva Magalhães
Supervisor: Julian Francis Richmond Paton
Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
Institution abroad: University of Auckland, New Zealand  
Associated to the scholarship:19/24060-9 - Contribution of the parafacial Respiratory Group to the inspiratory, expiratory and cardiovascular responses of rats to muscle afferent fiber stimulation, BP.DR

Abstract

Hypertension (high blood pressure) continues to be a major global problem despite an armoury of anti-hypertensive medications. At least 50% of treated hypertensives remain with uncontrolled blood pressure, and this is most likely due to high sympathetic activity, which is not reduced by contemporary anti-hypertensive medication. The carotid body (CB) has emerged as a novel target to lower sympathetic activity. This project aims to understand the mechanisms of CB aberrant activity and will test the hypothesis that the sympathetic innervation of the vasculature of this organ is intensified in spontaneously hypertensive (SH) relative to Wistar (normotensive) rats and, when activated, causes more profound vasoconstriction that triggers afferent sensitisation. We will assess differences in autonomic nervous innervation of the vasculature of the CB between rat strains. We have built a state-of-the-art physiological imaging platform that allows visualisation of the entire circulation of the intact CB of rats. We will use both an in vitro isolated carotid artery bifurcation preparation containing the CB and carotid sinus nerve as well as the working heart brainstem preparation. We will measure changes in both the arterial/arteriole diameter and flow velocity through the CB during stimulation and antagonism of the adrenergic nervous system and compare data temporally with responses in carotid sinus nerve activity in Wistar and SH rats. This will allow for the first time an assessment of how alterations in flow through the CB affect its afferent sensitivity and whether improving CB perfusion will reduce its excitability state in the SH rat, thereby reducing sympathetic tone. (AU)

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