Histochemical Demonstration of 11β-Hydroxysteroid Dehydrogenase in Ampullae of Semicircular Canals

Abstract

Htovski DZ. Histochemical demonstration of 11β-hydroxysteroid dehydrogenase in ampullae of semicircular canals. Acta Otolaryngol (Stockh) 1996; 116: 737-740.

The enzyme 11β-hydroxysteroid dehydrogenase (11βHSD) plays a major role in the protection of the mineralocorticoid (type I) receptor. the cellular mechanism of aldosterone selectivity relies on the coexpression of mineralocorticoid receptors and 11βHSD in the same cells. An 11βSHSD activity has been localized in the ampullae of the semicircular canal by histochemical technique which links steroid metabolism with the deposition of formazan deposition. Oxidation of 11β-hydroxyandrostenedione was observed in the dark-cell region. Oxidation of 11β-hydroxyandrostenedione was nicotine-adenine dinucleotide (NAD) dependent. These results demonstrate the presence of a dehydrogenase activity separate from the nicotineamide-adenine dinucleotide phosphate (NADP) dependent 11βHSD.

Key Words:

• dark cells
• vestibule Na K-ATPase
• ion transport
• mineralocorticoids
• glucocorticoids