Platelet accumulation in regions of low blood flow during the postischemic period.

Various studies indicate that after a latent interval, a progressive focal deterioration of microvascular perfusion can develop in zones of acute damage to the central nervous system (CNS). In order to obtain reliable information concerning the possibility of platelet participation in this phenomenon, platelet deposition was investigated by means of 111Indium-labeled platelets, and compared with local cerebral blood flow (CBF) and cortical sensory evoked response (CSER). Studies were performed with a model of focal ischemia in which small volumes of air were injected selectively into one internal carotid artery of dogs anesthetized with alpha chloralose throughout the experiment. The ischemic period was followed by a 10-min, 60-min or 4-hr recovery period. The main result was a prominent and diffuse accumulation of platelets in zones of low CBF in dogs subjected to 4 hr recovery.