Faculty Collaboration Database

Renal interstitial corticosterone and 11-dehydrocorticosterone in conscious rats. Am J Physiol Renal Physiol 2007 Jul;293(1):F186-92

Date

03/29/2007

Pubmed ID

17389675

DOI

10.1152/ajprenal.00484.2006

Scopus ID

2-s2.0-34548042789 (requires institutional sign-in at Scopus site)   22 Citations

Abstract

Deficiencies in the conversion between active and inactive glucocorticoids in the kidney can lead to hypertension. However, the significance of glucocorticoid metabolism in specific kidney regions in vivo is not clear, possibly in part due to the difficulty in measuring glucocorticoid levels in kidney regions in vivo. We used microdialysis techniques to sample renal interstitial fluid from conscious rats. The levels of corticosterone (active) and 11-dehydrocorticosterone (inactive) were analyzed by liquid chromatography-tandem mass spectrometry. Direct infusion of the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) inhibitor carbenoxolone into the renal medulla induced hypertension, and significantly increased corticosterone levels and the corticosterone/11-dehydrocorticosterone ratio, an index of 11beta-HSD activity, in the renal medullary microdialysate, but not in urine or the plasma. Further characterization of conscious, untreated rats (n = 13-16) indicated that corticosterone concentrations (ng/ml) were 0.8 +/- 0.1, 1.0 +/- 0.1, 66.7 +/- 8.1, and 7.9 +/- 1.1 in cortical microdialysate, medullary microdialysate, the plasma, and urine, respectively. The corticosterone/11-dehydrocorticosterone ratios were 0.8 +/- 0.1, 0.6 +/- 0.1, 10.6 +/- 1.4, and 1.7 +/- 0.1, respectively, in these 4 types of sample. The expression level of 11beta-HSD1 was higher in the medulla than in the cortex, whereas 11beta-HSD2 was most enriched in the outer medulla. Microdialysate levels of corticosterone were approximately 1.6-fold higher in afternoons than in mornings, whereas plasma levels differed by 2.8-fold. These results demonstrated that corticosterone excess in the renal medulla might be sufficient to cause hypertension and provided the first characterization of renal interstitial glucocorticoids.

Author List

Usa K, Singh RJ, Netzel BC, Liu Y, Raff H, Liang M

Author

Hershel Raff PhD Professor in the Academic Affairs department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

11-beta-Hydroxysteroid Dehydrogenases
Animals
Blood Pressure
Blotting, Western
Carbenoxolone
Circadian Rhythm
Corticosterone
Enzyme Inhibitors
Immunohistochemistry
Kidney
Kidney Medulla
Male
Microdialysis
Potassium
Rats
Rats, Sprague-Dawley
Reverse Transcriptase Polymerase Chain Reaction
Sodium
Tandem Mass Spectrometry