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Arterial baroreflex function in toads Rhinella schneideri: temperature effect, hydration state and role of renin-angiotensin system

Grant number: 12/17379-0
Support Opportunities:Scholarships in Brazil - Doctorate
Effective date (Start): July 01, 2014
Effective date (End): October 31, 2016
Field of knowledge:Biological Sciences - Physiology - Compared Physiology
Principal Investigator:Kênia Cardoso Bícego
Grantee:Lucas Aparecido Zena
Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil


Various environmental or anthropogenic stressors can influence amphibians' life cycle. Fluctuations in temperature can cause substantial changes in cardiorespiratory variables in these animals, reflecting effects on peripheral vascular resistance, cardiac contractile activity, intrinsic sinoatrial node firing rate, as well as ventilation. Few studies report baroreflex responses in different species of vertebrates and little is known about thermal influences on the feedback loop regulation of blood pressure (BP) in amphibians. Interactions between cardiovascular and respiratory systems operate coordinately to match oxygen delivery to demand in an ectotherm and thereby increasing oxygen consumption can be achieved when animal experience high environmental temperatures. It has been suggested that ventilation might be part of the BP feedback loop regulation in mammals, as well as in amphibians; however, no data exist related to relationship between BP and ventilation against different metabolic demands imposed by temperature. We have recently reported an increase in cardiac baroreflex sensitivity along with a clear cardiac reflex response mainly to hypotension at all three temperatures tested (15, 25 and 30°C) in the South American savanna-related toad Rhinella schneideri. These findings indicate that these toads present temperature dependence for cardiac limb of the barostatic response and the cardiac baroreflex response is primarily hypotensive rather than hypertensive, similar to crocodilians and mammals. Thus, the cardiac baroreflex response and ventilation will be determined by increases induced by phenylephrine (alpha 1-adrenergic agonist) and decreases caused by sodium nitroprusside (a nitric oxide donor) in systemic arterial BP of toads. The cardiac limb of barorreflex evaluation will be comprised by the sigmoid curves analyses in addition to ventilation measurements (breathing frequency and tidal volume) at 25 and 35oC. Animals will also be submitted to hyperoxia to assess the possible involvement of peripheral chemoreflex. (AU)

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Scientific publications (5)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ZENA, LUCAS A.; GARGAGLIONI, LUCIANE H.; BICEGO, KENIA C.. Temperature effects on baroreflex control of heart rate in the toad, Rhinella schneideri. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY, v. 179, p. 81-88, . (08/57712-4, 12/17379-0)
ZENA, LUCAS A.; LEITE, CLEO A. C.; LONGHINI, LEONARDO S.; DIAS, DANIEL P. M.; DA SILVA, GLAUBER S. F.; HARTZLER, LYNN K.; GARGAGLIONI, LUCIANE H.; BICEGO, KENIA C.. Analysis of the respiratory component of heart rate variability in the Cururu toad Rhinella schneideri. SCIENTIFIC REPORTS, v. 7, . (08/57712-4, 12/17379-0, 14/12190-1, 13/17606-9)
ZENA, LUCAS A.; DA SILVA, GLAUBER S. F.; GARGAGLIONI, LUCIANE H.; BICEGO, KENIA C.. Baroreflex regulation affects ventilation in the cururu toad Rhinella schneideri. Journal of Experimental Biology, v. 219, n. 22, p. 3605-3615, . (08/57712-4, 12/17379-0)
ZENA, LUCAS A.; DANTONIO, VALTER; GARGAGLIONI, LUCIANE H.; ANDRADE, DENIS V.; ABE, AUGUSTO S.; BICEGO, KENIA C.. Winter metabolic depression does not change arterial baroreflex control of heart rate in the tegu lizard Salvator merianae. Journal of Experimental Biology, v. 219, n. 5, p. 725-733, . (10/05063-2, 12/17379-0)
DA SILVA, GLAUBER S. F.; VENTURA, DANIELA A. D. N.; ZENA, LUCAS A.; GIUSTI, HUMBERTO; GLASS, MOGENS L.; KLEIN, WILFRIED. Effects of aerial hypoxia and temperature on pulmonary breathing pattern and gas exchange in the South American lungfish, Lepidosiren paradoxa. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY, v. 207, p. 107-115, . (08/57712-4, 12/17379-0, 14/12190-1, 13/17606-9)

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