OBJECTIVETo study the expression and distribution of aquaporin 3 (AQP3) and aquaporin 9 (AQP9) in colonic mucosa of patients with functional constipation, and to examine the relationship of constipation with AQP3 and AQP9.

METHODSImmunohistochemistry and semi-quantitative Western blotting were used to detect the expression and distribution of AQP3 and AQP9 in colonic mucosa of 45 patients with functional constipation (trial group) and 21 cases without constipation (control group). Gray scale ratios of AQP3 and AQP9 to beta-actin protein as interior reference were relative amounts of AQP3 and AQP9.

RESULTSImmunohistochemistry showed that AQP3 was distributed mainly in basement and cavosurface membrane of epithelial cell of colonic mucosa and AQP9 mainly in basement membrane of goblet cell in cavosurface colonic mucosa. Western blotting revealed that the average values of gray scale ratios of AQP3 in ascending colon of trial group and control group were 0.905 and 0.798 (P<0.05),while those of AQP9 were 0.544 and 0.543 (P>0.05), respectively. The average values of gray scale ratios of AQP3 in descending colon of trial group and control group were 0.697 and 0.701 (P>0.05), while those of AQP9 were 0.575 and 0.732 (P<0.05), respectively.

CONCLUSIONSUp-regulated expression of AQP3 in ascending colon and down-regulated expression of AQP9 in descending colon are presented in patients with functional constipation as compared to patients without functional constipation. AQP3 and AQP9 may play a significant role in the onset and development of constipation.