Evaluation of diamine oxidase activity (DAO) in the rat intestinal mucosa by measuring expiredCO after oral administration ofC-putrescine.

This study was performed to investigate whether mucosal diamine oxidase activity could be assessed by measuring expiredCO after oral administration ofC-putrescine. Immediately after giving 5 μCi ofC-putrescine, theCO was collected at 1-h intervals for 8 h into a vial containing 1 ml of 10 mM hyamine hydroxide, 2 ml of ethanol, and an appropriate amount of phenolphthalein dye. The expiredCO caused the color to disappear. The amount ofCO, determined by scintillation counting, reached a maximum 1 h afterC-putrescine administration, and gradually decreased thereafter. A positive correlation between the mucosal diamine oxidase activity and the maximal expiredCO value was obtained. There is no doubt that this test can be used to easily detect mucosal DAO activity and avoid the necessity of mucosal biopsy. [ABSTRACT FROM AUTHOR]