| Autor: |
Freitas SCF; Laboratório de Fisiologia Translacional, Universidade Nove de Julho, São Paulo, SP, Brasil., Dos Santos CP; Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil., Arnold A; Unidade de Hipertensão, Instituto do Coração, Faculdade de Medicina de São Paulo, São Paulo, SP, Brasil., Stoyell-Conti FF; Laboratório de Fisiologia Translacional, Universidade Nove de Julho, São Paulo, SP, Brasil.; DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA., Dutra MRH; Laboratório de Fisiologia Translacional, Universidade Nove de Julho, São Paulo, SP, Brasil., Veras M; Departamento de Patologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil., Irigoyen MC; Unidade de Hipertensão, Instituto do Coração, Faculdade de Medicina de São Paulo, São Paulo, SP, Brasil., De Angelis K; Laboratório de Fisiologia Translacional, Universidade Nove de Julho, São Paulo, SP, Brasil.; Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil. |
| Abstrakt: |
Several studies have focused on the heart rate variability (HRV) of murine species, while studies discussing HRV in murine neonates and infants remain scarce, since recording hemodynamic signals through invasive methods in small animals has been found to be quite challenging. Thus, this study aimed at describing and validating a novel method to assess HRV in newborn rats. An electrocardiogram (ECG) system was used to determine RR intervals in awake newborns and evaluate HRV in normotensive (Wistar) and hypertensive (SHR) neonate rats. After birth, ECG was recorded in the awake newborns, and they were allowed to rest on a heated surface, restricted only by the weight of the adhesive ECG electrodes. The electrodes were cut and adapted to provide more comfort to the animal, and gently placed on the newborn's skin. RR intervals were recorded over a 30-min period using an ECG system together with LabChart software (4 KHz). Three sequences of 5 min each from the ECG recording period were analyzed in time and frequency domains, using CardioSeries software. ECG data resulted in a clearly interpretable signal that was used to generate an RR interval sequence through time for the analysis of HRV. SHR neonates presented increased cardiac sympathovagal balance compared to Wistar neonates (low frequency/high frequency: 3.85±0.71 vs 0.90±0.09). In conclusion, the ECG setup here described may be used to record RR intervals to assess HRV in neonate rats, thus detecting early impairment of HRV in hypertensive newborns. |
