Relationship between 22Na distribution and cerebral blood flow in ischemic gerbil brain

Sodium transport in the early postischemic period was studied using Mongolian gerbils with right common carotid artery ligation. [22Na]sodium chloride ([22Na]NaCl) was infused immediately after, 10 minutes before, and 4 hours before carotid ligation, and the 22Na distribution was measured in symptomatic animals by autoradiography 1 hour after ischemia. Regional cerebral blood flow was determined by [14C]iodoantipyrine autoradiography. The specific gravity of the brain was measured in symptomatic gerbils 1 and 2 hours after carotid ligation by a gradient column. There was a low uptake of 22Na in the ischemic core and a high uptake in the ischemic periphery when the tracer was given 10 minutes before or immediately after ischemia. In contrast, tracer given 4 hours before ischemia showed an increased radioactivity in both the ischemic core and periphery. It is suggested that increased sodium in the ischemic core is due to a decreased sodium clearance rate and increased sodium in the ischemic periphery is due to some active transport process.