title: Plasma steroid profiling and response to trophins to illustrate intra-adrenal dynamics.
abstract: The importance of corticosteroids in cardiovascular and other chronic disease is recognised. In addition, plasma steroid precursor-to-product ratios are useful and convenient indirect indicators of efficiency of key steroidogenic enzymes (aldosterone synthase, 11β-hydroxylase and 17α-hydroxylase). The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has enabled measurement of numerous corticosteroid compounds simultaneously. However, normal responses to trophins and variation in salt intake are not well described. This study examined these parameters in a large group of healthy volunteers. Sixty normotensive volunteers were recruited and underwent infusion of angiotensin II (AngII) and ACTH, following low- and high-salt diet. Measurement of plasma steroids at baseline and 30 min after infusion of trophin was carried out by LC-MS. As expected, plasma mineralocorticoid levels increased in response to salt restriction and were suppressed with salt loading; ACTH infusion increased all corticosteroids, while AngII increased mineralocorticoids and suppressed glucocorticoid production. ACTH increased S:F but decreased DOC:B, thus the S:F ratio is a more appropriate index of 11β-hydroxylase efficiency. The B:F ratio increased following ACTH treatment and salt restriction. A larger proportion of plasma B than generally accepted may be derived from the zona glomerulosa and this ratio may be most informative of 17α-hydroxylase activity in salt-replete subjects. Although DOC:aldosterone, B:aldosterone and 18-hydroxyB:aldosterone should provide indices of aldosterone synthase efficiency, responses of individual compounds to trophins suggest that none of them accurately reflect this. Based on these data, aldosterone synthase activity is most accurately reflected by aldosterone concentration alone.
authors.affiliation: Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK Frances.McManus@glasgow.ac.uk.
authors.forename: F
authors.initials: F
authors.lastname: McManus
authors.affiliation: Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: R
authors.initials: R
authors.lastname: Fraser
authors.affiliation: Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: E
authors.initials: E
authors.lastname: Davies
authors.affiliation: Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: J M C
authors.initials: JM
authors.lastname: Connell
authors.affiliation: Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: E M
authors.initials: EM
authors.lastname: Freel
mesh_terms: D000293:Adolescent; D000302:Adrenal Cortex / Q000187:drug effects* / Q000378:metabolism*; D000305:Adrenal Cortex Hormones / Q000097:blood*; D000324:Adrenocorticotropic Hormone / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D042702:Angiopoietin-2 / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage
chemical_list: D000305:Adrenal Cortex Hormones; D042702:Angiopoietin-2; D017673:Sodium Chloride, Dietary; D000324:Adrenocorticotropic Hormone
keywords: adrenal; corticosteroid; enzyme