The contribution of peripheral chemoreflex to the vagal control of the heart during recovery from exercise in healthy subjects

• Grant number: 16/23622-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): February 01, 2017
• Effective date (End): December 31, 2017
• Field of knowledge: Biological Sciences - Physiology - Physiology of Effort
• Principal Investigator: Bruno Moreira Silva
• Grantee: Indyanara Cristina Ribeiro
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

The responses of the cardiovascular system to exercise occur, mainly, due to mechanisms of the neural control of the circulation that promote a sympathetic activity stimulation and vagal reduction, leading to a increase of cardiovascular determinants, as the heart rate. The end of exercise is accompanied by a vagal reactivation that promotes a large decrease of heart rate, thus the recovery of this variable has been used as an indicator of cardiac vagal modulation. One of the possible mechanisms involved on autonomic adjustments during exercise is the peripheral chemoreflex, since this reflex has been shown to be potentiated by metabolic acidosis, among other mechanisms related to exercise.However, it is still unclear the tonic contribution of this reflex to the vagal control of the heart after exercise, which then will be the focus of investigation of the present project. Our hypothesis is that the peripheral chemoreflex contributes to the vagal control of the heart during the recovery from physical exercise. To test this hypothesis, we will recruit 15 male healthy subjects (18-35 years old). During the post-exercise recovery, all of them will be randomly exposed to 3 situations: 1) hyperoxia (inhibition of the peripheral chemoreflex via inhalation of 100% O2); 2) hypoxia (stimulation of the peripheral chemoreflex via inhalation of 12% O2); or 3) normoxia (control experiment via inhalation of 21% O2). The vagal control of the heart will be evaluated by the heart rate recovery and heart rate variability, both methods that are pharmacologically validated and reproducible. In case of hypothesis confirmation, the results could ellucidate one of the possible mechanisms involved in cardiac autonomic modulation after exercise (AU)

Scientific publications

(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)

PAULA-RIBEIRO, MARCELLE; RIBEIRO, INDYANARA C.; ARANDA, LILIANE C.; SILVA, TALITA M.; COSTA, CAMILA M.; RAMOS, ROBERTA P.; OTA-ARAKAKI, JAQUELINA; CRAVO, SERGIO L.; NERY, LUIZ E.; STICKLAND, MICHAEL K.; et al. Cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension at rest and during orthostatic stress: role of the peripheral chemoreflex. Journal of Applied Physiology, v. 131, n. 2, p. 794-807, AUG 2021. (16/01155-6, 15/22198-2, 16/23622-5, 14/24294-6)

PAULA-RIBEIRO, MARCELLE; RIBEIRO, INDYANARA C.; ARANDA, LILIANE C.; SILVA, TALITA M.; COSTA, CAMILA M.; RAMOS, ROBERTA P.; OTA-ARAKAKI, JAQUELINA S.; CRAVO, SERGIO L.; NERY, LUIZ E.; STICKLAND, MICHAEL K.; et al. Carotid chemoreflex activity restrains post-exercise cardiac autonomic control in healthy humans and in patients with pulmonary arterial hypertension. JOURNAL OF PHYSIOLOGY-LONDON, v. 597, n. 5, p. 1347-1360, MAR 1 2019. (15/22198-2, 16/23622-5, 14/24294-6, 16/01155-6)