Autoregulation of Cerebral Blood Flow in Young and Aged Spontaneously Hypertensive Rats (SHR)

Abstract
Autoregulation of cerebral blood flow (CBF) to controlled hemorrhagic hypotension was studied in young adult spontaneously hypertensive rats (SHR, 3.4 mo. of age) and aged SHR (20.3 mo.). There were no differences in average values for mean arterial pressure and baseline CBF between the 2 groups of rats. During hypotension CBF was more reduced in aged SHR than in young SHR, indicating that the lower limit of cerebral autoregulation is shifted to a higher level in aged SHR. Such upward shift of the autoregulation is likely due to a long-lasting hypertension which may lead to the diminished vasodilatory response of the brain to hypotension.