POSTISCHEMIC HYPOPERFUSION IN TRANSIENT GLOBAL-ISCHEMIA - A ROLE FOR ENDOTHELINS

The role of endogenous endothelins (ETs) in mediating postischemic hyp operfusion after transient global ischemia was investigated in halotha ne-anesthetized rats. Pretreatment with the broad spectrum ET(A) and E T(B) antagonist bosentan (17 mu mol/kg) had minimal effect on postisch emic hypoperfusion, as measured by hydrogen clearance, in the caudate nucleus and the parietal cortex during 3 h after bilateral common caro tid artery occlusion with concomitant hemorrhagic hypotension (transie nt global ischemia). In cerebral blood flow (CBF) measured by [C-14]io doantipyrine autoradiography at 90 min after carotid occlusion with co ncomitant hemorrhagic hypotension, bosentan treatment failed to alter CBF in any of the cerebral cortical regions examined. No changes in CB F, as measured by hydrogen clearance, were observed after transient bi lateral common carotid artery occlusion. [C-14]Iodoantipyrine autoradi ography at 90 min post occlusion failed to demonstrate any increases i n cerebral blood flow after transient bilateral common carotid artery occlusion in any of the 35 brain regions examined in anesthetized rats .