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ORIGINAL ARTICLE
Year : 2022  |  Volume : 65  |  Issue : 4  |  Page : 171-178

Spectral analysis of cardiovascular oscillations in the 7-day regimen of losartan administration with and without cold stress


1 Department of Psychiatry, Cheng Hsin General Hospital; Department of Physiology, National Defense Medical Center, Taipei, Taiwan
2 Division of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan
3 Department of Physiology, National Defense Medical Center, Taipei, Taiwan
4 Department of Physiology; Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
5 Department of Physiology, National Defense Medical Center; Division of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan

Correspondence Address:
Prof. Che-Se Tung
Division of Medical Research and Education, Cheng Hsin General Hospital, No. 45, Cheng Hsin St., Beitou, Taipei 11280
Taiwan
Prof. Shi-Hung Tsai
Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei
Taiwan
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0304-4920.354802

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Spectral analysis of heart rate (HR) and blood pressure (BP) variabilities (BPV and HRV) is widely available and utilized in understanding the dynamic cardiovascular autonomic regulation in a variety of pathophysiological conditions. In conscious cold-stressed (CS) rats, we examined the effect of a 7-day regimen administration of losartan, a selective nonpeptide angiotensin AT1 receptor blockade, on BPV and HRV at three frequency components: very-low frequency (VLF), low frequency (LF), and high frequency (HF). Key findings in changes of systolic BP (SBP), HR, and spectral power densities for cardiopulmonary oscillations (HF), sympathetic oscillations (LF), cardiovascular myogenic oscillations (VLF), and overall autonomic activity total power (TP) showed: (I) In the resting PreCS trial, compared with the saline, losartan increased HFBPV, TPHRV, all three HRV frequency powers, and the occurrence of the dicrotic notch (DN). However, it decreased SBP, HR, and the LFBPV frequency power. (II) In the CS trial, losartan significantly decreased SBP and DN occurrence and HR and LF/HFHRV but significantly increased HFHRV, TPBPV, and all three BPV frequency powers. In addition, similar to the saline, losartan showed positively correlated LFBPV and VLFBPV. Conversely, losartan converted the original inverse correlations between LFHRV and LFBPV of CS to a positive correlation. (III) Compared with saline in PreCS and CS trials, losartan detached the corresponding sympathetic oscillations between LFBPV and LFHRV. The overall result indicates that endogenous angiotensin II, through stimulation of the AT1 receptor, augments sympathetic tone but attenuates sympathetic oscillations in rats, particularly under the stressful cooling impacts.


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