Contribution of venous return to increased ventilation pulmonary during the beginning of physical exercise

• Grant number: 21/11209-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2022
• End date: December 31, 2022
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Bruno Moreira Silva
• Grantee: Larissa de Freitas Campos
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated research grant: 17/17027-0 - Hormonal systems in renal and cardiovascular diseases: from cell biology to new physiological paradigms with advances for therapeutics, AP.TEM

Abstract

Several cardiorenal diseases evolve with hyperactivation of the renin-angiotensin-aldosterone system, which generates multiple consequences, including increased plasma volume in the blood. Increased blood volume can cause a large displacement of blood from the limbs for the heart at the beginning of the exercise, by the effect of the muscular pump. Maybe in this situation, the venous return contributes to generating excessive ventilator response to exercise in patients with cardio-renal diseases and, consequently, may be involved in the generation of feeling of dyspnea. The rationale behind this hypothesis is based on experiments under controlled conditions in decerebrate or anesthetized animal models. A lot of studies were done on humans in an attempt to translate the findings into animal models. However, so far, the role of increased venous return in response regulation ventilation at the beginning of the physical exercise in humans remains uncertain. Therefore, such a gap will be the subject of investigation of this project. Our hypothesis is that attenuation of venous return will reduce the ventilator response to the beginning of the physical exercise. To test the project hypothesis, young and healthy adults will exercise on an ergometric bicycle, against low resistance, with and without manipulation of the venous return through cuff inflation positioned on the thighs. We will measure lung ventilation and expired gases by sensors attached to an orinasal mask. In addition, we will measure multiple variables of cardiovascular diseases to characterize the manipulation of venous return, as well as measuring perceptual variables, such as the verbal report about the level of willingness to to inspire. (AU)