1lβ-Hydroxysteroid Dehydrogenase in Vascular Smooth Muscle and Heart: Implications for Cardiovascular Responses to Glucocorticoids*

The enzyme 11β-hydroxysteroid dehydrogenase (11β-OHSD) converts the active glucocorticoid corticosterone to inactive 11-dehydrocorticosterone in the rat (or cortisol to cortisone in man), thereby protecting renal mineralocorticoid receptors from corticosterone or cortisol and allowing preferential access for aldosterone. We have previously demonstrated that cortisol-induced cutaneous vasoconstriction in man is potentiated by the 11β-OHSD inhibitor glycyrrhetinic acid, suggesting that 11β-OHSD may protect vascular corticosteroid receptors. In this study we report quantitation of 11β-OHSD bioactivity in homogenates of rat aorta, mesenteric artery, caudal artery, and heart, expressed as the percent in vitro conversion of 3H-corticosterone to 3H-ll-dehydrocorticosterone. Nicotinamide adenine dinucleotide phosphate (NADP+)-dependent 11β-OHSD activity was found in all of these tissues and was significantly higher in resistance vessels than aorta (P < 0.05) [without NADP+: caudal artery (4.2 ± 0.2%) = mesenteric...