Use of non-linear analyzes of heart rate variability in horses submitted to selective blocks of the autonomic nervous system and training

• Grant number: 23/16353-1
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2024
• End date: January 31, 2028
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: José Corrêa de Lacerda Neto
• Grantee: Gabriel Vieira Ramos
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The application of non-invasive techniques to evaluate equine athletes has become an object of study in several areas of equine medicine. Among these, heart rate variability (HRV) stands out as a way of evaluating sympathovagal balance through the intervals between successive normal R waves (RRi or NNi). HRV comprises linear (time [TD] and frequency [FD] domains) and non-linear analyzes for quantifying sympathetic and parasympathetic activity on cardiovascular modulation. However, in horses little is known about non-linear HRV parameters such as sample entropy (SampEnt) and symbolic dynamics (SymbDin) and their relationship with the activity of the branches of the autonomic nervous system (ANS) on the heart. That said, the present study aims to evaluate linear (TD and FD) and non-linear (SampEnt and SymbDin) variables in 12 healthy horses during rest and after selective pharmacological blockade of the sympathetic (propranolol; 0.2 mg/kg) and parasympathetic branches. (atropine; 0.04 mg/kg). Furthermore, given the influence of physical conditioning on the modulation of the ANS on the heart, the present study will also evaluate the animals after six-week conditioning based on the maximum lactate steady state (MLSS), both at rest and after the selective blockade of the ANS. Regarding conditioning assessment, the animals will be divided into two groups: control group (CG, n = 6) and trained group (TG, n = 6). The RRi intervals will be extracted from electrocardiographic exams with an average duration of 50 minutes.