These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Changes in autonomic activity and baroreflex sensitivity with the hypertension process and age in rats.
    Author: Nagai R, Nagata S, Fukuya F, Higaki J, Rakugi H, Ogihara T.
    Journal: Clin Exp Pharmacol Physiol; 2003; 30(5-6):419-25. PubMed ID: 12859436.
    Abstract:
    1. Autonomic activity and baroreflex sensitivity (BRS) were compared in age-matched conscious groups of Wistar Kyoto (WKY) rats, spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP). 2. Male WKY rats, SHR and SHRSP aged 4-30 weeks were used. Autonomic activity and BRS were estimated by power spectral and cross-spectral analysis of systolic blood pressure (SBP) and SBP-SBP (SS) interval fluctuations, respectively. 3. The time-course of heart rate (HR), SBP, the amplitude of the low-frequency component of SBP fluctuation (SBP-LF; prazosin-sensitive index) and the amplitude of the high-frequency component of the SS interval fluctuation (SS-HF; atropine-sensitive index) consisted of two periods. In the first period (up to 10 or 15 weeks of age), BP, SBP-LF and SS-HF increased with age. The order of SBP-LF was SHRSP > SHR > WKY rats throughout this period. During the second period, BP was sustained at certain levels in all strains, but changes in SBP-LF and SS-HF with age were different among strains. In particular, in SHRSP, SBP-LF markedly decreased with age after 10 weeks. Baroreflex sensitivity in WKY rats increased gradually with age, whereas the BRS in SHR and SHRSP decreased before 6 weeks of age and remained lower than that in WKY rats. 4. In conclusion, the present study shows that both prazosin-sensitive and atropine-sensitive indices are associated with the elevation of BP in all strains studied. However, hypertension after 15 weeks of age in SHRSP is sustained despite a paradoxical reduction in sympathetic activity with an abnormal control of BRS. Therefore, the contribution of autonomic activity to hypertension may be discussed separately as a developmental period and a sustained period.
    [Abstract] [Full Text] [Related] [New Search]