Association between heart rate, heart rate variability, cortisol, glucose and electrolytes in healthy newborn calves

D.A.C Quevedo,C.A.D Bolaños,A Alfonso,S.B Chiacchio,E Oba,M.L.G Lourenço,R.K Takahira

doi:10.1590/1678-4162-10461

Abstract

ABSTRACT This study aims at evaluating the effects of electrolytes, glucose and cortisol levels over heart rate (HR) and heart rate variability (HRV) in healthy newborn calves. Seventeen healthy Holstein calves were evaluated during their first month of life, and the plasma concentrations of glucose, cortisol, calcium, magnesium, inorganic phosphorus, sodium and potassium were analyzed. HRV indexes were determined in the time and frequency domains through the analysis of neonatal electrocardiogram recordings. In the first day, low blood levels of phosphorus presented a strong correlation with the HR and the increased high-frequency components of HRV. The plasma concentrations of magnesium decreased significantly throughout the 35 days, revealing a positive association with a decreasing low-frequency components of HRV at day 28. There was a strong correlation between HR, HRV indexes, some plasma electrolytes, glucose and cortisol during the studied period. Variations in the concentrations and correlations observed may be attributed to the adaptive neonatal period in calves.

Highlights

Heart rate variability (HRV) refers to the periodic changes in duration of cardiac cycles, which can be measured as the successive intervals between beat-to-beat intervals (Kovács et al, 2014)
Sampling time had a significant effect on the potassium, magnesium, phosphorous, calcium and cortisol levels, while the sodium and glucose levels presented no significant changes during the first month of life
On the first week of life, calcium concentrations showed a downward trend from the first day (10.3±0.9mg/dL) throughout the entire month until day 35, when the lowest value (8.7±1.2mg/dL) was registered with statistical significance (P≤ 0.01)

Summary

Introduction

Heart rate variability (HRV) refers to the periodic changes in duration of cardiac cycles, which can be measured as the successive intervals between beat-to-beat intervals (Kovács et al, 2014). It is based on the antagonistic oscillatory influences of the sympathetic and parasympathetic nervous system on the sinoatrial node and is used as an indicator of Autonomic Nervous System (ANS) activity in response to stress (Mohr et al, 2002). Studies have shown the usefulness of the LF/HF ratio of the power spectrum, with increases in the ratio interpreted as a regulatory shift towards sympathetic dominance (Akselrod et al, 1985; Abboud and Sadeh, 1990). High vagal tone has been linked to efficient autonomic regulatory activity, which enables an organism to increase its sensitivity and response to physiological and environmental challenges (Von Borell et al, 2007)

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