Expression and significance of aquaporin 4 in the colonic mucosa of patients with slow transit constipation

OBJECTIVE: To explore the relationship between the expression of aquaporin 4 (AQP4) and slow transit constipation(STC). METHODS: The expression of AQP4 in the ascending colon mucosa of 45 patients with STC was detected by immunohistochemistry. The transit time of stool was measured with barium sulfate suspensions. Stool was classified using Bristol stool chart. The difference between the pre- and post-operation groups was analyzed. RESULTS: Of 45 STC patients, 36 had high AQP4 expression (high expression group) and 9 had low AQP4 expression(low expression group). Preoperatively 30(83.3%) patients in the high expression group and 3(3/9) patients in the low expression group presented dry and hard stool (type I( or II()(P<0.01). Postoperatively, stool pattern was improved in all the patients of high expression group. One patient in low expression group still presented dry and hard stool(P<0.01). Preoperatively the transit time was(127.3+/-28.2) h in high expression group and (64.2+/-12.9) h in low expression group(P<0.01). Postoperatively, the transit time was (17.3+/-7.0) h in high expression group and (28.0+/-12.6) h in low expression groups(P<0.01). CONCLUSION: High expression of AQP4 accelerates the water absorption in colon mucosa and may be one of the crucial events in the development of STC.