Local hemodynamic changes during transient middle cerebral artery occlusion and recirculation in the rat: a [14C]iodoantipyrine autoradiographic study.

We evaluated acute alterations of local cerebral perfusion following 30 min of transient right proximal middle cerebral artery (MCA) clip-occlusion in the rat and following two intervals of postischemic reperfusion. Local cerebral blood flow (lCBF) was assessed by [14C]iodoantipyrine autoradiography. Brain temperature was controlled at 35.5-36.5 degrees C throughout the experiment. We measured lCBF in four groups of rats: (a) sham-operated controls (n = 5), (b) following 30 min MCA occlusion (n = 5), (c) following 30 min of MCA occlusion with 15-min reperfusion (n = 6) and (d) following 30 min of MCA with 120-min reperfusion (n = 6). lCBF was measured in seven regions of the ischemic and non-ischemic hemispheres. MCA occlusion induced an ipsilateral reduction of lCBF, which was most severe in the parietal cortex (8.4 +/- 4.0% of control, mean +/- S.D.), and dorsolateral caudoputamen (20.0 +/- 13.4% of control). lCBF in the non-ischemic hemisphere and in ipsilateral regions lying outside the MCA territory also decreased significantly. lCBF recovery was incomplete when assessed following only 15 min of reperfusion. Reperfusion of 120 min led to return of cortical CBF to control levels, but lCBF in the caudoputamen remained depressed (50-55% of control values). Caudoputaminal CBF and cortical CBF values were highly correlated with one another under normal and ischemic conditions, but this correlation was disrupted following reperfusion. On the basis of these results, we speculate that, if a means were found to enhance the early recovery of lCBF following transient ischemia, this might expand the therapeutic window of opportunity for the institution of other neuroprotective strategies.