The ALP activities and properties of rat intestine cut into 20 segments were examined, and we were able to demonstrate that the ALP activity of upper intestine is high compared to that of lower intestine. This result coincided with those of other reports. However, we newly clarified that there is an ALP isoenzyme found in the lower intestine which can be inhibited by L-homoarginine. The molecular weight of the ALP isoenzyme was 136 kDa. In addition, it was clarified that there are several

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... ymes from upper to lower intestine. This study demonstrates that there exist isoenzymes, which are inhibited by L-HArg, in the intestine which are similar to the isoenzymes in the liver, bone and kidney. Key words: alkaline phosphatase (ALP), intestine, isoenzyme, L-homoarginine (L-HArg), rat by a high fat diet, ALP has been thought to be related to the absorption of fatty acid, carbohydrate, amino acid and protein from the intestine. We have found that the activities of ALP in the intestine or in serum are changed depending on the feeding conditions and have had an interest in factors which modulate the quantity of ALP protein and the activity of ALP. In a study on inhibitory effects of various compounds, it was reported that intestinal ALP is specially inhibited by L-phenylalanine (L-Phe), but not by L-homoarginine (L-HArg) [5, 15] . However, in this study we found that there are some intestinal ALP isoenzymes inhibited by L-HArg. The purpose of this study was to demonstrate the properties of intestinal ALP isoenzymes by polyacrylamide gel electrophoresis (PAGE).