Mutually distinctive gradients of three types of intestinal alkaline phosphatase along the longitudinal axis of the rat intestine.
OBJECTIVE
A descending gradient of alkaline phosphatase (AP) activity is well known to exist in the rat intestine. To understand the physiological role(s) of intestinal AP (IAP), we examined in detail the distribution of IAP subtypes along the longitudinal axis of the rat intestine.


METHODS
The consecutive 2-cm segments of the upper intestine were analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) followed by staining for IAP activity. The reverse transcription-polymerase chain reaction was conducted to assess the relative levels of tissue mRNA for the 2 distinct genes of rat IAP, rIAP-I and rIAP-II.


RESULTS
A descending gradient of IAP activity was found along the upper small intestine, where 3 bands of the activity, termed types 1, 2 and 3 from the anode were located on SDS-PAGE gels. Along the longitudinal axis, types 1 and 3 showed ascending and descending gradients, respectively; whereas type 2 had a broad uniform distribution. The mRNA level for rIAP-I showed an ascending distribution, and that of rIAP-II, a descending one. Type 3 IAP was drastically diminished in duodenum of cysteamine-ulcer rats, but type 1 remained constant.


CONCLUSIONS
These distinctive gradients of IAP subtypes may provide a clue to scrutinize the physiological significance of AP in the rat intestine, which is a flow system with polarity.
Shidoji
Yoshihiro
Y
Laboratory of Cellular Biochemistry, Graduate School of Human Health Sciences, Siebold University of Nagasaki, Nagayo, Nagasaki, Japan. shidoji@sun.ac.jp
Kim
Soon Hie
SH
D000469:Alkaline Phosphatase / Q000032:analysis / Q000494:pharmacology*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D041981:Gastrointestinal Tract / Q000201:enzymology*; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar
D007527:Isoenzymes; D012333:RNA, Messenger; D000469:Alkaline Phosphatase