Effects of immobilization stress on cerebral blood flow and cerebrovascular permeability in spontaneously hypertensive rats.

Immobilization of unanesthetized, freely breathing, 10-12 month-old, spontaneously hypertensive rats (SHR) did not significantly alter regional cerebral blood flow (rCBF) in 13 of 14 brain regions assayed. After 5 or 15 min of immobilization, rCBF was unchanged except at the frontal lobe, where it rose significantly by 21%. Furthermore, immobilization did not increase the cerebrovascular permeability-area product for 14C-sucrose, except at three brain regions. The results indicate that immobilization of SHR does not significantly affect rCBF or blood-brain barrier permeability in most regions of the brain, and suggest that adequate autoregulation of rCBF is maintained under stress.