Lisinopril Indifferently Improves Heart Rate Variability During Day and Night Periods in Spontaneously Hypertensive Rats

Abstract

<jats:p>The aim of this work was to investigate the effect of 10 weeks of lisinopril treatment to spontaneously hypertensive rats (SHRs) on day/night variations of blood pressure, heart rate and autonomic cardio-regulation parameters. Male SHR with surgically implanted radio-telemetry implant that provided direct measurements of arterial pressure and electrocardiogram wave were used. Animals were allocated to two groups (n=5 each). The first group was treated with lisinopril (20 mg/kg by gavage) daily for 10 weeks (treated group); whereas the second was gavaged daily with tap water (untreated group). Arterial blood pressure, ECG and other telemetry parameters were recorded at the start and at the end of 10-week treatment. Collected data were analyzed using specialized software and were statistically tested. In addition to the expected lowering of blood pressure, spectral analysis of R-R intervals revealed that lisinopril treatment for 10 weeks significantly caused 2-3 fold increase in heart rate variability (HRV) during both active and inactive periods. However, R-R interval durations demonstrated variable distribution patterns during those periods. The cause of observed distribution pattern of R-R intervals during active and inactive periods may be of significance to better understand HRV changes and warrants further investigations.</jats:p>

Diurnal, seasonal, and sex patterns of heart rate in grip-restrained African giant rats (Cricetomys gambianus, Waterhouse)

“…), during the “inactive period” of the day (Albarwani et al. ), and with mild psychological stress (Feetham and Barrett‐Jolley ). It is conceivable that the HRV in AGRs may be elevated/higher during the rainy season, in does, during the afternoon (since AGRs are nocturnal), and in free‐moving, unrestrained rats.…”

Cardiac autonomic activity has a circadian rhythm in summer but not in winter in non-lactating pregnant dairy cows

“…the high-frequency (HF) component as an indicator of vagal regulation and the ratio between the low-frequency (LF) and the HF band (LF/HF) are appropriate indices reflecting stress in dairy cattle [19]. For studying the autonomic modulation of cardiac activity, monitoring the rhythmic patterns in heart rate and HRV is of scientific interest in humans [20][21][22] and in laboratory species in both health and disease [23][24][25][26]. The observations made in rodents and humans indicate that cardiac autonomic function is synchronized with the time of day.…”

Parameters of spectral analysis of heart rate variability in rats

“…Since 60 oscillations/min correspond to the frequency of 1 Hz, 150 oscillations/min should do the frequency of 2.5 Hz. In some papers right this frequency (2.5 Hz) has been proposed as the upper limit of HF-waves range [10,14,22,33], but После тщательной обработки данных ЭКГ (точная маркировка RR-интервалов) можно выполнить расстановку диапазонов частот для спектрального анализа. Однако в некоторых публикациях авторы не указывают эти диапазоны, что может поставить под сомнение правильность их выводов [12].…”

“…Nowadays there are different notions about a range of slow waves, especially their lower limits (0.005-1 Hz) [1,24,26,40,56,57].…”

“…Большинство исследователей определили диапазон LF-волн от 0,19-0,2 Гц до 0,7-0,8 Гц [17,27,33,45,67]. В работах А.П.…”