Dynamic pressure - Flow relationship of the cerebral circulation during acute increase in arterial pressure

Rong Zhang, Khosrow Behbehani, Benjamin D. Levine

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

The physiological mechanism(s) for the regulation of the dynamic pressure-flow relationship of the cerebral circulation are not well understood. We studied the effects of acute cerebral vasoconstriction on the transfer function between spontaneous changes in blood pressure (BP) and cerebral blood flow velocity (CBFV) in 13 healthy subjects (30 ± 7 years). CBFV was measured in the middle cerebral artery using transcranial Doppler. BP was increased stepwise with phenylephrine infusion at 0.5, 1.0 and 2.0 μg kg-1 min-1. Phenylephrine increased BP by 11, 23 and 37% from baseline, while CBFV increased (11%) only with the highest increase in BP. Cerebrovascular resistance index (BP/CBFV) increased progressively by 6, 17 and 23%, demonstrating effective steady-state autoregulation. Transfer function gain at the low frequencies (LF, 0.07-0.20 Hz) was reduced by 15, 14 and 14%, while the phase was reduced by 10, 17 and 31%. A similar trend of changes was observed at the high frequencies (HF, 0.20-0.35 Hz), but gain and phase remained unchanged at the very low frequencies (VLF, 0.02-0.07 Hz). Windkessel model simulation suggests that increases in steady-state cerebrovascular resistance and/or decreases in vascular compliance during cerebral vasoconstriction contribute to the changes in gain and phase. These findings suggest that changes in steady-state cerebrovascular resistance and/or vascular compliance modulate the dynamic pressure-flow relationship at the low and high frequencies, while dynamic autoregulation is likely to be dominant at the very low frequencies. Thus, oscillations in CBFV are modulated not only by dynamic autoregulation, but also by changes in steady-state cerebrovascular resistance and/or vascular compliance.

Original languageEnglish (US)
Pages (from-to)2567-2577
Number of pages11
JournalJournal of Physiology
Volume587
Issue number11
DOIs
StatePublished - 2009

ASJC Scopus subject areas

  • Physiology

Fingerprint Dive into the research topics of 'Dynamic pressure - Flow relationship of the cerebral circulation during acute increase in arterial pressure'. Together they form a unique fingerprint.

  • Cite this