G. Florence et al., SPREADING DEPRESSION REVERSIBLY IMPAIRS AUTOREGULATION OF CORTICAL BLOOD-FLOW, The American journal of physiology, 266(4), 1994, pp. 180001136-180001140
The experiment examines whether the mechanisms responsible for the aut
oregulation of cerebral blood flow (CBF) in response to hypotension we
re affected during the initial phase of cortical spreading depression
(CSD). CSD was induced by a cortical pinprick in anesthetized rabbits,
and CBF was measured by laser-Doppler flowmetry through a chronically
implanted Plexiglas window. The reactivity to CO2 and papaverine was
also studied before and after CSD. Fifteen minutes after CSD, autoregu
latory vasodilation was reduced (P < 0.01). This impairment was revers
ible, since the autoregulatory response was restored 35 min after CSD.
The time course of the reactivity to papaverine after CSD paralleled
the autoregulatory response, with a significant correlation between th
e two reactivities (r = 0.47; P < 0.01). Conversely, the reactivity to
CO2 was significantly reduced after CSD (P < 0.001) and remained affe
cted for at least 95 min. We conclude that the mechanisms underlying a
utoregulation are transiently disturbed by CSD and that these mechanis
ms are not mediated by an accumulation of CO2 but seem instead to be r
elated to an increase in adenosine 3',5'-cyclic monophosphate concentr
ation.