Distribution of 11 beta-hydroxysteroid dehydrogenase along the rat intestine.

Aldosterone selectivity of mineralocorticoid target tissues has been suggested to be due to the inactivation of glucocorticoids in the target tissue by 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD). The distribution of 11 beta-OHSD was studied in the intestine which is composed of aldosterone-sensitive and insensitive segments. The activity of the enzyme was high in distal colon and medium in ileum, cecum, and proximal colon. Zero activity was found in duodenum and jejunum. Carbenoxolone completely blocked the enzyme. Low-salt diet increased the activity in proximal colon and decreased in ileum. Adrenalectomy decreased the activity in ileum and proximal colon. The existence of segmental differences in the distribution of 11 beta-OHSD and the hormonal effect on the activity of the enzyme suggest a physiological role of 11 beta-OHSD in the intestine.