Mechanisms maintaining cerebral perfusion during systemic hypotension are impaired in elderly adults.

Autor: Abdali K; Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA., Chen X; Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA.; Jishou University, Jishou 416000, China., Ross S; Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA., Davis S; Departments of Internal Medicine, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA., Zhou Z; Departments of Biostatistics & Epidemiology, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA., Mallet RT; Departments of Physiology and Anatomy, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA., Shi X; Departments of Pharmacology and Neuroscience, The University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
Jazyk: angličtina
Zdroj: Experimental biology and medicine (Maywood, N.J.) [Exp Biol Med (Maywood)] 2023 Dec; Vol. 248 (23), pp. 2464-2472. Date of Electronic Publication: 2023 Dec 06.
DOI: 10.1177/15353702231209416
Abstrakt: Postural hypotension abruptly lowers cerebral perfusion, producing unsteadiness which worsens with aging. This study addressed the hypothesis that maintenance of cerebral perfusion weakens in the elderly due to less effective cerebrovascular autoregulation and systemic cardiovascular responses to hypotension. In healthy elderly ( n  = 13, 68 ± 1 years) and young ( n  = 13, 26 ± 1 years) adults, systemic hypotension was induced by rapid deflation of bilateral thigh cuffs after 3-min suprasystolic occlusion, while heart rate (HR), mean arterial pressure (MAP), and blood flow velocity of the middle cerebral artery (V MCA ) were recorded. V MCA /MAP indexed cerebrovascular conductance (CVC). Durations and rates of recovery of MAP and V MCA from their respective postdeflation nadirs were compared between the groups. Thigh-cuff deflation elicited similar hypotension and cerebral hypoperfusion in the elderly and young adults. However, the time elapsed (T Δ ) from cuff deflation to the nadirs of MAP and V MCA , and the time for full recovery (T R ) from nadirs to baselines were significantly prolonged in the elderly subjects. The response rates of HR (ΔHR, i.e. cardiac factor), MAP (ΔMAP, i.e. vasomotor factor), and CVC following cuff deflation were significantly slower in the elderly. Collectively, the response rates of the cardiac, vasomotor, and CVC factors largely explained T RVMCA . However, the T RVMCA /ΔMAP slope (-3.0 ± 0.9) was steeper ( P  = 0.046) than the T RVMCA /ΔHR slope (-1.1 ± 0.4). The T RVMCA /ΔCVC slope (-2.4 ± 0.6) was greater ( P  = 0.072) than the T RVMCA /ΔHR slope, but did not differ from the T RVMCA /ΔMAP slope ( P  = 0.52). Both cerebrovascular autoregulatory and systemic mechanisms contributed to cerebral perfusion recovery during systemic hypotension, and the vasomotor factor was predominant over the cardiac factor. Recovery from cerebral hypoperfusion was slower in the elderly adults because of the age-diminished rates of the CVC response and cardiovascular reflex regulation. Systemic vasoconstriction predominated over increased HR for restoring cerebral perfusion after abrupt onset of systemic hypotension.
Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Databáze: MEDLINE
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