AbstractThe elevation of serum alkaline phosphatase (ALP) that develops in the dog after 24 hours of colon ischemia was studied to determine its tissue origin.Portal, hepatic, and aortic blood were sampled but no difference in ALP level among these sites was found.In sera shown to have a significant rise in ALP, other tests of liver function were unchanged from normal, suggesting the ALP did not originate from the liver.On electrophoresis the “ischemic ALP” migrated faster than a known liver ALP standard but more slowly than an intestinal ALP sam