Evidence of a cerebrovascular postarteriole windkessel with delayed compliance

J Cereb Blood Flow Metab. 1999 Jun;19(6):679-89. doi: 10.1097/00004647-199906000-00012.

Abstract

A pronounced temporal mismatch was observed between the responses of relative cerebral blood volume (rCBV) measured by magnetic resonance imaging and relative cerebral blood flow measured by laser-Doppler flowmetry in rat somatosensory cortex after electrical forepaw stimulation. The increase of relative cerebral blood flow after stimulus onset and decrease after stimulus cessation were accurately described with a single exponential time constant of 2.4 +/- 0.8 seconds. In contrast, rCBV exhibited two distinct and nearly sequential processes after both onset and cessation of stimulation. A rapid change of rCBV (1.5 +/- 0.8 seconds) occurring immediately after onset and cessation was not statistically different from the time constant for relative cerebral blood flow. However, a slow phase of increase (onset) and decrease (cessation) with an exponential time constant of 14 +/- 13 seconds began approximately 8 seconds after the rapid phase of CBV change. A modified windkessel model was developed to describe the temporal evolution of rCBV as a rapid elastic response of capillaries and veins followed by slow venous relaxation of stress. Venous delayed compliance was suggested as the mechanism for the poststimulus undershoot in blood oxygen-sensitive magnetic resonance imaging signal that has been observed in this animal model and in human data.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Algorithms
  • Animals
  • Arterioles / physiology
  • Blood Volume / physiology
  • Cerebrovascular Circulation / physiology*
  • Compliance
  • Humans
  • Laser-Doppler Flowmetry
  • Magnetic Resonance Imaging
  • Male
  • Models, Neurological
  • Rats
  • Rats, Sprague-Dawley
  • Stress, Physiological / physiopathology