Effects of sodium intake, age, gender, blood sampling time on distribution of plasma aldosterone, renin activity, deoxycorticosterone, cortisol, cortisone, and 24 h urinary aldosterone levels in normotensive individuals based on LC-MS/MS.

PURPOSE: This study aims to analyze the distribution of plasma aldosterone, renin activity, deoxycorticosterone (DOC), cortisol, cortisone, and 24 h urinary aldosterone (24 h-uAld) levels based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. MATERIALS AND METHODS: Plasma and 24 h urine were collected from 129 healthy volunteers in Northeast China. The effect of sodium intake, age, gender, blood sampling time on plasma aldosterone concentration (PAC), plasma renin activity (PRA), PAC to PRA ratio (ARR), DOC, cortisol, cortisone, cortisol to cortisone ratio, and 24 h-uAld were investigated by nonparametric test, multiple linear regression and Harris-Boyd's standard deviate test. RESULTS: There was no significant difference observed in 24 h-uAld, PAC (AM), PRA(AM), ARR (AM), DOC (AM), cortisol (AM), cortisone (AM), and cortisol to cortisone (AM) between high and low sodium intake group. Significant differences were observed between morning and afternoon sampling groups in terms of PAC, ARR, DOC, cortisol, and cortisone. Reference intervals (RIs) of 24 h-uAld, PAC (AM) were recommended to be partitioned by gender. RI of PRA was recommended age stratification. CONCLUSION: We recommend that the same reference interval could be used regardless of sodium intake. Gender is the main influence factor for 24 h-uAld, PAC, and ARR. Age is key influence factor for PRA.

Urinary corticosteroid excretion predicts left ventricular mass and proteinuria in chronic kidney disease.

Blockade of the MR (mineralocorticoid receptor) in CKD (chronic kidney disease) reduces LVMI [LV (left ventricular) mass index] and proteinuria. The MR can be activated by aldosterone, cortisol and DOC (deoxycorticosterone). The aim of the present study was to explore the influence of mineralocorticoids on LVMI and proteinuria in patients with CKD. A total of 70 patients with CKD and 30 patients with EH (essential hypertension) were recruited. Patients underwent clinical phenotyping; biochemical assessment and 24 h urinary collection for THAldo (tetrahydroaldosterone), THDOC (tetrahydrodeoxycorticosterone), cortisol metabolites (measured using GC-MS), and urinary electrolytes and protein [QP (proteinuira quantification)]. LVMI was measured using CMRI (cardiac magnetic resonance imaging). Factors that correlated significantly with LVMI and proteinuria were entered into linear regression models. In patients with CKD, significant predictors of LVMI were male gender, SBP (systolic blood pressure), QP, and THAldo and THDOC excretion. Significant independent predictors on multivariate analysis were THDOC excretion, SBP and male gender. In EH, no association was seen between THAldo or THDOC and LVMI; plasma aldosterone concentration was the only significant independent predictor. Significant univariate determinants of proteinuria in patients with CKD were THAldo, THDOC, USod (urinary sodium) and SBP. Only THAldo excretion and SBP were significant multivariate determinants. Using CMRI to determine LVMI we have demonstrated that THDOC is a novel independent predictor of LVMI in patients with CKD, differing from patients with EH. Twenty-four hour THAldo excretion is an independent determinant of proteinuria in patients with CKD. These findings emphasize the importance of MR activation in the pathogenesis of the adverse clinical phenotype in CKD.

Excretion of norsteroids' phase II metabolites of different origin in human.

The urinary phase II metabolites of norsteroids, 19-norandrosterone, 19-noretiocholanolone and 19-norepiandrosterone glucuronide and sulphate, were analyzed in samples collected during the pregnancy, following the administration of norsteroids or the consumption of edible parts of non-castrated pig and in athletes' samples in which they were found during routine controls. The level of the sulfo- and glucuroconjugated metabolites was precisely determined by GC/HRMS, after selective hydrolysis. The goal was to evaluate whether the fine analysis of the norsteroid conjugates produced and excreted in different conditions would show a pattern that could be linked to their origin. The delta (13)C values of the metabolites formed following the ingestion of edible parts of non-castrated pig were measured by isotope ratio mass spectrometry. Our results indicated that it is not possible to determine the origin of the urinary metabolites based upon the sole evaluation of the different metabolites and conjugates. The GC/C/IRMS is the only method permitting to distinguish between the exogenous and endogenous origin of the metabolites.

Origin of urinary nonconjugated 19-nor-deoxycorticosterone and metabolism of infused radiolabeled 19-nor-deoxycorticosterone in men and women.

It is known that 19-nor-deoxycorticosterone (19-nor-DOC) is a potent mineralocorticosteroid that is present in urine of rats and humans in a free, i.e., nonconjugated, form. In some forms of hypertension in rats, the levels of free 19-nor-DOC in urine are increased compared with those in urine of normotensive animals. Yet, despite the potential importance of this mineralocorticosteroid in the pathogenesis of certain forms of hypertension, little is known of its site of origin or metabolism. In the present investigation, we evaluated the metabolism of intravenously infused [3H]19-nor-DOC and the possibility that 19-nor-DOC was formed from plasma DOC. We found that the metabolism of [3H]19-nor-DOC infused intravenously in men and women was similar to that of DOC with important exceptions. The majority of the radiolabeled urinary metabolites of intravenously infused [3H]19-nor-DOC were excreted in urine as glucuronosides. Little radioactivity, infused as [3H]19-nor-DOC, was recovered in urine as nonconjugated or sulfoconjugated steroids. There was no free radiolabeled 19-nor-DOC in urine after the simultaneous infusion of [3H]19-nor-DOC and [14C]DOC. A major metabolite of [3H]19-nor-DOC in urine was 19-nor-DOC-21-glucuronoside, whereas little or no intravenously infused radiolabeled DOC was excreted as radiolabeled DOC-glucuronoside. We also found that intravenously infused [14C]DOC was not converted to urinary [14C]19-nor-DOC (glucuronoside) and that other tritium-labeled metabolites of infused [3H]19-nor-DOC contained no carbon-14. The production rate of 19-nor-DOC, computed from the specific activity of urinary 19-nor-DOC (glucuronoside), in one normal man was 16 micrograms/d and in the two women of this study, it was 10 micrograms/d. These findings are supportive of the proposition that free urinary 19-nor-DOC is not formed from plasma DOC; it may be formed in kidney from a precursor other than DOC or it may be formed nonenzymatically in kidney or urine from a precursor such as 19-oic-DOC.

19-nor-deoxycorticosterone excretion in rats bred for susceptibility and resistance to the hypertensive effects of salt.

Rats susceptible (S/JR) and resistance (R/JR) to the hypertensive effect of salt were weaned at 28 days of age and placed on a high salt intake. Blood pressure, measured at 4-5 and 8-9 weeks of age (after 5 weeks of high salt intake), demonstrated a slight increase in R/JR rats and a highly significant increase in S/JR rats. Urinary fee 19-nor-deoxycorticosterone (19-nor-DOC) levels measured in weekly urine collections were found to be markedly elevated in S/JR rats compared to levels in R/JR rats. Since 19-nor-DOC has been shown to be a potent mineralocorticoid, the results suggest that elevated production of 19-nor-DOC may have a role in hypertension in rats susceptible to the hypertensive effects of salt.

19-Nordeoxycorticosterone excretion in male and female inbred salt-sensitive (S/JR) and salt-resistant (R/JR) Dahl rats.

Rats were selectively bred for susceptibility (S) and resistance (R) to the hypertensinogenic effects of excess salt intake by Dahl and further inbred to virtual homozygosity by Rapp (S/JR and R/JR). The S strain has been shown to have a mutation of the cytochrome P-450-dependent 11 beta,18-hydroxylase resulting in the enhanced production of 18-hydroxydeoxycorticosterone (18-OH-DOC) compared to that of the R strain. It is known that this enzyme is also responsible for the hydroxylation of deoxycorticosterone at the 19 position to produce 19-hydroxydeoxycorticosterone. Recently, the excretion of 19-nordeoxycorticosterone (19-nor-DOC), a potent mineralocorticoid, has been shown to be markedly increased in S/JR females compared to that in R/JR females consuming a high sodium diet. While the S/JR rat is spontaneously hypertensive, the course of the disease is greatly accelerated and exacerbated by a high sodium diet. If, indeed, 19-nor-DOC is responsible for the spontaneous hypertension in the S/JR rat, then its production should also be higher in the S/JR rat consuming a normal salt diet. Furthermore, since its production is suppressed by NaCl intake, the excretion should be even higher when not suppressed by a high sodium diet. We measured the urinary excretion of 19-nor-DOC, 18-OH-DOC, and corticosterone in male and female S/JR and R/JR rats consuming a normal sodium diet. The excretions of corticosterone and 18-OH-DOC were significantly higher by S/JR of both sexes than by R/JR, with the excretion by female rats being higher than that by male rats within the same strain. The hierarchy of excretion rates of 19-nor-DOC was: S/JR females greater than R/JR females greater than S/JR males greater than R/JR male rats. These studies indicate that while S/JR rats of both sexes develop higher blood pressures than the R/JR even on a standard salt intake, the excretion of 19-nor-DOC does not correlate well with their blood pressure elevation, since the normotensive female R/JR rat excretes significantly higher quantities of 19-nor-DOC than the hypertensive male S/JR rat. Thus, it is unclear whether 19-nor-DOC is playing a significant role in the pathogenesis of the hypertension in the S/JR rat. It also remains unknown whether the renal site of formation of 19-nor-DOC allows access to the mineralocorticoid target sites in the kidney.

Radioimmunoassay for urinary free 19-nor-deoxycorticosterone: effects of adrenocorticotropin and sodium depletion.

A RIA for urinary free deoxycorticosterone (DOC) and 19-nor-deoxycorticosterone [21-hydroxy-19-nor-4-pregnene-3,20-dione (19-nor-DOC)] was developed and used to measure urinary free DOC and 19-nor-DOC in rats kept on normal and low sodium diets and before and after ACTH administration. The RIA required a preliminary high performance liquid chromatography purification using a Lichrosorb diol column before the eluates were assayed using highly specific antibodies. The intraassay variability was 9.8% for DOC and 10% for 19-nor-DOC; the interassay variabilities were 19% and 16%, respectively. Urinary free DOC excretion was 0.71 +/- 0.15 ng/day (mean +/- SD) in rats maintained on a normal sodium diet and 1.42 +/- 0.46 ng/day after 3 days of a sodium-restricted diet. Urinary free 19-nor-DOC was 10.5 +/- 5.5 ng/day in rats kept on the normal sodium diet and 28.6 +/- 11.5 ng/dl after 3 days of a sodium-restricted diet. ACTH increased the excretion of urinary free DOC from 0.72 +/- 0.2 to 4.62 +/- 2.3 ng/day and that of 19-nor-DOC from 5.37 +/- 2.8 to 10.15 +/- 2.5 ng/day. These data indicate that the adrenal precursor of 19-nor-DOC probably comes from both the zona fasciculata and the glomerulosa to explain the ACTH and sodium depletion responses.

Biphasic 19-nor-deoxycorticosterone excretion after adrenal enucleation is associated with altered adrenal mitochondrial cytochrome P450 11 beta-, 18-, and 19-hydroxylase activities.

After adrenal enucleation (AE) rats avidly retain sodium (early phase), but after 7-10 days they lose this sodium avidity (late phase). Although increased production of a mineralocorticoid, 19-nor-deoxycorticosterone (19-Nor-DOC), has been implicated, 19-Nor-DOC levels during the early and late phases of AE have not been systematically measured. Furthermore it is not known why 19-Nor-DOC production should increase during a time when production of 11 beta- and 18-hydroxylated corticosteroids are decreased in AE. The purpose of this study was to examine the 11 beta, 18-, and 19-hydroxylase pathways in the early and late phases of AE. The results demonstrate increased urinary 19-Nor-DOC and decreased 18-OH-DOC and corticosterone excretion in the early phase of AE at a time when adrenal mitochondrial 11 beta- and 18-hydroxylase activities were decreased but 19-hydroxylase activity was unchanged. During the late phase of AE, urinary 19-Nor-DOC had decreased and 18-OH-DOC and corticosterone had increased to levels indistinguishable from those in sham controls. This reduction in 19-Nor-DOC was associated with a decrease in 19-hydroxylase activity in AE. Since the 11 beta, 18-, and 19-hydroxylases have a common substrate (DOC), it is possible that differential flux of DOC through these pathways could account for the changes in steroid production in AE. These data suggest that the increased 19-Nor-DOC excretion in AE may be due to alterations in enzyme activity leading to a shunting of DOC into the 19-Nor-DOC pathway. In addition, the synchronicity of 19-Nor-DOC with sodium excretion suggests that it has an important role in the pathogenesis of the sodium retention in AE.

The role of the adrenal gland in hypertensive transgenic rat TGR(mREN2)27.

The TGR(mREN2)27 is a new monogenetic rat model in hypertension research. As the mouse Ren-2d renin gene is integrated into their genome, they develop fulminant hypertension between 5 and 15 weeks of age, with blood pressure maxima of 300 mm Hg. Their plasma renin-angiotensin system (RAS) is suppressed, but the transgene is highly expressed in the adrenal gland, so we investigated its possible role in steroid metabolism and the pathogenesis of hypertension. During the phase of hypertension development (between 6-18 weeks), the urinary excretion of deoxycorticosterone (DOC), corticosterone (B), 18-hydroxycorticosterone, and aldosterone is 1.5- to 2.5-fold elevated compared with that in Sprague-Dawley (SD) rats (P less than 0.0005) despite the suppressed plasma RAS. Moreover, the adrenal gland in TGR(mREN2)27 shows an increased maximal response to ACTH stimulation in regard to urinary excretion of DOC (after ACTH, 244 +/- 42 ng/24 h in TGR; 62 +/- 10 ng/24 h in SD; P less than 0.0005) and B (after ACTH, 5144 +/- 346 ng/24 h in TGR; 2607 +/- 324 ng/24 h in SD; P less than 0.0005). Additionally, plasma prorenin in TGR was stimulated more than 10-fold, indicating transgene regulation by ACTH. Since spironolactone treatment did not lower the blood pressure in TGR, hypertension solely due to hypermineralocorticoism is unlikely. Our results indicate that the adrenal steroid metabolism is markedly stimulated in young TGR, and the absolute increase in urinary DOC and B after ACTH injections is enhanced, possibly due to a stimulated local intraadrenal RAS.

Origin and production rates of deoxycorticosterone and deoxycorticosterone sulfate in men and nonpregnant women.

In the present investigation, we evaluated the origin of deoxycorticosterone sulfate (DOC-SO4) and the production rates of DOC and DOC-SO4 in men and women. Previously, we found that there was little or no interconverion of plasma DOC and DOC-SO4; this finding was reconfirmed in the present investigation. After the iv infusion of [3H]DOC-SO4 and [14C]DOC, urine was collected for 5 days, DOC-SO4 was isolated and purified as unconjugated DOC, and tetrahydro-DOC glucuronoside was isolated and purified as the unconjugated metabolite. The production rate of DOC in these subjects (mean +/- SEM, 66 +/- 9.8 micrograms/24 h) was computed from the specific activity of urinary [14C]tetrahydro-DOC (glucuronoside); the production rate of DOC-SO4 in these subjects (92 +/- 15.9 micrograms/24 h) was computed from the specific activity of urinary [3H]DOC-SO4. The production rates are expressed on the basis of the molecular weight of DOC. Since plasma DOC and DOC-SO4 are not interconverted, we conclude that both steroids are secretory products, presumably from the adrenal cortex.

Urinary free 19-nor-deoxycorticosterone and deoxycorticosterone in human hypertension.

The urinary excretion of deoxycorticosterone (DOC) and 19-nor-deoxycorticosterone (19-nor-DOC) was measured using a technique which consisted of the purification of both steroids by high pressure liquid chromatography followed by RIA using specific antibodies. The urinary excretion of DOC was 29.4 +/- 25 ng/24 h (mean +/- SD) in 35 normal subjects, 26 +/- 21 ng/24 h in 46 patients with low renin hypertension (LRHT), and 32 +/- 23 ng/24 h in 16 patients with normal renin hypertension (NRHT). The urinary excretion of 19-nor-DOC was 287 +/- 178 ng/24 h in normal subjects, 224 +/- 167 ng/24 h in LRHT patients, and 235 +/- 170 ng/24 h in NRHT patients. There were no hypertensive patients with increased excretion of 19-nor-DOC. The excretion of 19-nor-DOC increased after 3 days of sodium depletion in normal and hypertensive subjects, but the increment was significantly higher in normotensive subjects. There was no correlation between the excretion of 19-nor-DOC and that of DOC or urinary aldosterone. This study suggests that DOC or 19-nor-DOC does not play a role in the pathogenesis of either LRHT or NRHT and disagrees with previous reports suggesting such a role.

Unconjugated and conjugated urinary 19-nor-deoxycorticosterone glucosiduronate. Elevated levels in essential hypertension.

The mineralocorticoid 19-nor-deoxycorticosterone (19-nor-DOC) is present in the urine of rats and humans in unconjugated and conjugated forms. This study sought to compare levels of unconjugated and conjugated 19-nor-DOC glucosiduronate in essential hypertensive subjects. The essential hypertensive and normal subjects were admitted to a metabolic unit, and plasma and urine were collected at fixed intervals on a fixed-electrolyte intake (Na+, 128 mEq/day, K+, 80 mEq/day). The 19-nor-DOC was purified by chromatography and measured by radioimmunoassay. Unconjugated urinary 19-nor-DOC was elevated in essential hypertensive subjects (195 +/- 21 [SE] ng/day; n = 21) compared with levels in normal subjects (118 +/- 30 [SE] ng/day; n = 13, p less than 0.05). Two essential hypertensive subjects had very high levels (673, 729 ng/day), while levels in seven essential hypertensive subjects were below 118 ng/day. Conjugated 19-nor-DOC glucosiduronate also was elevated in essential hypertensive subjects (950 +/- 88 [SE] ng/day; n = 8) compared with levels in normal subjects (680 +/- 90 [SE] ng/day; n = 5). Seven of eight essential hypertensive subjects had levels greater than 680 ng/day. The unconjugated and conjugated urinary 19-nor-DOC glucosiduronate levels were positively correlated in both of these groups (rho = 0.82, p less than 0.01). Other test results including plasma renin activity, plasma aldosterone levels, aldosterone secretion rates, and plasma and urine electrolyte levels were not different between groups. These results indicate that essential hypertensive subjects have increased 19-nor-DOC excretion, which is reflected by increases in both unconjugated and conjugated glucosiduronate forms.(ABSTRACT TRUNCATED AT 250 WORDS)

Low renin essential hypertension: failure to demonstrate excess 11-deoxycorticosterone production.

11-Deoxycorticosterone (DOC) was determined by specific RIA in 27 normal subjects and in 25 normal renin and 23 low renin hypertensives. None of the patients exhibited unprovoked hypokalemia. Strict criteria were employed for renin profiling the hypertensive patients, including age matching, exclusion of diabetics, and the use of medications known to interfere with the renin response or with DOC measurements. In all 3 groups, comparable DOC levels were found in plasma and urine. In contrast, DOC was elevated in 7 of 19 patients with primary aldosteronism. These results do not support a DOC excess hypothesis for the syndrome of low renin essential hypertension.

Production rate of deoxycorticosterone in women during the follicular and luteal phases of the ovarian cycle: the role of extraadrenal 21-hydroxylation of circulating progesterone in deoxycorticosterone production.

The fractional conversion of plasma progesterone to deoxycorticosterone (DOC) ([rho]BU P-DOC) has been determined in pregnant, nonpregnant, and adrenalectomized women and men. The [rho]BU P-DOC varies widely among persons, but the [rho]BU P-DOC in a given subject is invariant regardless of plasma progesterone concentrations. In the present investigation we sought to ascertain 1) the production rate of DOC (PR-DOC) during the follicular and luteal phases of the ovarian cycle of women and 2) the role of extraadrenal 21-hydroxylation of progesterone as a source of DOC during the luteal phase of the ovarian cycle. Four subjects were given iv infusions of [3H]progesterone and [14C]DOC in order to determine [rho]BU P-DOC and the PR-DOC during both phases of the ovarian cycle. The [rho]BU P-DOC found in these subjects were within the range of values previously reported, viz. 0.007 +/- 0.001 (mean +/- SEM), and did not change during the cycle. The mean daily PR-DOC in these subjects during the follicular phase of the menstrual cycle was 58 microgram/24 h, whereas the mean daily PR-DOC during the luteal phase was 318 microgram/24 h. In each subject the PR-DOC during the luteal phase was 4--7 times greater than the PR-DOC during the follicular phase of the cycle. The increase in plasma concentrations of DOC during the luteal phase of the ovarian cycle apparently results from extraadrenal formation of DOC from circulating progesterone.

Plasma and urinary 19-nor-deoxycorticosterone in 17 alpha-hydroxylase deficiency syndrome.

17 alpha-hydroxylase deficiency syndrome (17-OHDS) is associated with hypogonadism, hypertension, and hypokalemia. Aldosterone production, however, is not elevated, and therefore, other known or unknown mineralocorticoids must account for the excess in mineralocorticoid activity. This study sought to determine whether 19-nor-deoxycorticosterone (19-nor-DOC), a potent hypertensinogenic mineralocorticoid, was elevated in this syndrome. Plasma and urine from a young woman with 17-OHDS were examined from various corticosteroids before and after ACTH, dexamethasone, and cortisol administration. In the basal state, urinary and plasma 17-hydroxycorticosteroids were decreased, but 17-deoxycorticosteroids were extremely elevated, including corticosterone (B), 18-hydroxy-B (18-OH-B), tetrahydro-B (TH-B), TH-DOC, and 18-OH-TH-DOC. Basal urinary (UF) 19-nor-DOC measured by both high pressure liquid chromatography (4255 ng/day) and RIA [3800 ng/day; normal, 102 +/- 27 (+/- SD), was markedly elevated. UF 19-nor-DOC did not increase further after ACTH administration (4255 ng/day), but it decreased after both dexamethasone (less than 100 ng/day) and cortisol therapy (612 and 218 ng/day). Basal plasma 19-nor-DOC was elevated and increased after ACTH stimulation (366 pg/ml) and decreased during dexamethasone suppression (6 pg/ml). A plasma 19-nor-DOC precursor that converted to nor-DOC upon acidification (perhaps 19-oic-DOC) also was detectable (172 pg/ml). This study, therefore, demonstrates a marked elevation in UF 19-nor-DOC in 17-OHDS, which could account for some of the excess mineralocorticoid activity in this syndrome.

Relationship of 19-nor-deoxycorticosterone to other mineralocorticoids in low-renin hypertension.

A number of mineralocorticoids have been proposed as etiologic factors in low-renin hypertension. In this study, urinary free 19-nor-deoxycorticosterone (UF 19-nor-DOC) was compared to other mineralocorticoids--aldosterone, deoxycorticosterone (DOC), and 18-OH-DOC, in 11 low-renin hypertensive patients on a controlled diet in a metabolic unit. Results demonstrated that both UF 19-nor-DOC and tetrahydro-DOC (TH-DOC) excretion were elevated (2086 +/- 926, nl = 339-579 ng/day, and 18 +/- 7, nl = 5-15 mcg/day, respectively), and positively correlated (r = 0.95). Neither 18-OH-DOC nor aldosterone secretion rates were elevated, and neither of these hormones correlated with UF 19-nor-DOC, with exception of the supine plasma aldosterone (SPA) (r = 0.86). In conclusion, both UF 19-nor-DOC and TH-DOC were increased and positively correlated in the present series of hypertensives. This association is possibly indicative of a precursor-product relationship between DOC and 19-nor-DOC. 19-Nor-DOC, furthermore, correlated with supine plasma aldosterone (SPA), which could, in part, reflect their shared adrenocorticotropic hormone (ACTH) dependence.

19-nor-deoxycorticosterone excretion in primary aldosteronism and low renin hypertension.

Nonaldosterone mineralocorticoids, such as deoxycorticosterone (DOC) and 18-hydroxy-DOC, have been reported to be elevated in some patients with primary aldosteronism (PA). Since DOC is a probable precursor of a more potent mineralocorticoid, 19-nor-deoxycorticosterone (19-nor-DOC), this study evaluated urinary free (UF) 19-nor-DOC excretion in 6 patients with PA and compared the results to those from 11 patients with low renin hypertension (LRH) and 7 normotensive subjects. PA was due to either an aldosterone-producing adenoma (APA; 4 patients) or bilateral adrenal hyperplasia (2 patients) diagnosed by adrenal venous catheterization or surgery. Compared to LRH subjects, patients with PA had a higher mean blood pressure (137 +/- 9 vs. 114 +/- 3 mm Hg), a lower plasma potassium level (3.1 +/- 0.2 vs. 3.9 +/- 0.1 meq/1) and greater renin suppression (0.3 +/- 0.1 vs. 0.6 +/- 0.1 ng angiotensin I/ml . h). UF 19-nor-DOC levels were elevated in PA subjects compared to those in normotensives (3,716 +/- 1,517 vs. 428 +/- 112 ng/day) but not compared to those in LRH patients (1,237 +/- 471). Two patients with APA had distinctly elevated UF 19-nor-DOC levels (11,137 and 7,744 ng/day), but another APA patient had the lowest value (305 ng/day). UF 19-nor-DOC positively correlated with the aldosterone secretion rate in PA (r = 0.75) but not LRH subjects. In conclusion, this study demonstrates that patients with PA may have elevated levels of UF 19-nor-DOC which are proportional to the aldosterone excess and could be a contributing factor to the hypertension, hypokalamia, and excess mineralocorticoid activity of this disease.

Converting-enzyme inhibitor administration lowers urinary free 19-nor-deoxycorticosterone levels.

19-Nor-deoxycorticosterone (19-nor-DOC) is a human mineralocorticoid. The regulation of its secretion is poorly understood, as renin angiotensin II (ANG II) stimulation has minimal effects on 19-nor-DOC. This study sought to determine if ANG II inhibition would decrease 19-nor-DOC production. Six normal subjects on fixed electrolyte intake were admitted to a metabolic unit. After a 5-day control period to establish electrolyte balance, enalapril, p.o., 10 mg/day, was administered for 28 days. This treatment resulted in ANG II inhibition, which was reflected by a rise in plasma renin activity, a blunting of the postural plasma aldosterone increment, and a decrease in aldosterone secretion rate (ASR). Levels of urinary free (UF) 19-nor-DOC progressively decreased from 294 +/- 108 ng/day on Day 0 to 164 +/- 70 on Day 3, 141 +/- 62 on Day 7, 101 +/- 38 on Day 14, 68 +/- 18 on Day 21, and 106 +/- 31 on Day 28. The decrease in 19-nor-DOC levels was synchronous with the fall in ASR (R = 0.94, n = 5, p less than 0.005), but it was of greater magnitude (71% decrease in 19-nor-DOC levels versus 41% decrease in ASR). In addition, the decrease in 19-nor-DOC levels correlated with a fall in urinary potassium and an increase in both urinary sodium and chloride (R = 0.68, -0.79, -0.87 respectively; n = 6, p less than 0.05). The fall in ASR, on the other hand, was not significantly correlated with the changes in these urinary electrolyte levels (R = 0.65, 0.64, 0.57 respectively; n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive effects of an aromatase inhibitor in the spontaneously hypertensive rat.

Recent studies from this laboratory have demonstrated that 19-nor-deoxycorticosterone, a potent mineralocorticoid, has been excreted in excess in the urine of young spontaneously hypertensive rats (SHR). Although urinary 19-nor-deoxycorticosterone levels decline before the onset of hypertension, preliminary evidence suggests that 19-nor-deoxycorticosterone is further oxygenated to other steroid products in older SHR. Since 19-hydroxylation is the essential first step in the formation of 19-nor-deoxycorticosterone from deoxycorticosterone and since the mechanism-based aromatase inhibitor 10-propargyl-androst-4-ene,3,17-dione preferentially inhibits 19-hydroxylation, this agent was administered to weanling SHR to determine whether inhibition of 19-nor-deoxycorticosterone formation could modify or prevent hypertension. Accordingly, either 10 mg of 10-propargyl-androst-4-ene,3,17-dione or vehicle (control) was injected daily for several weeks in 4.5 week-old SHR. Injection of 10-propargyl-androst-4-ene,3,17-dione reduced urinary free 19-nor-deoxycorticosterone and retarded the development of hypertension compared with the effect of vehicle injection (p less than 0.05). Mean blood pressure levels in SHR receiving 10-propargyl-androst-4-ene,3,17-dione were lower than those in SHR receiving vehicle for each of the first 8 weeks of treatment (p less than 0.05). These data support the importance of 10-nor-corticosteroids in the pathogenesis of hypertension in SHR.

Antihypertensive effects of an aromatase inhibitor in inbred salt-sensitive rats.

Rats susceptible to the hypertensive effect of dietary salt (SS/Jr) have excess urinary 19-nordeoxycorticosterone compared with salt-resistant control rats (SR/Jr). 19-Nordeoxycorticosterone is a hypertensinogenic mineralocorticoid, but whether it contributes to the salt sensitivity of SS/Jr is unknown. This study sought to evaluate the contribution of 19-nordeoxycorticosterone to the salt sensitivity of SS/Jr by lowering its production with an aromatase inhibitor, 10-propargyl-androst-4-ene,3,17-dione (19-acetylenic-androstenedione, 19-AA). This aromatase inhibitor also preferentially inhibits nonaromatizing adrenal 19-hydroxylation, an essential step in the formation of 19-nordeoxycorticosterone. To test this hypothesis, inhibitor (120 mg) or vehicle pellets were implanted into male and female weanling SS/Jr at 42 days of age. A high salt diet (8% NaCl) was started and two additional pellets were implanted at 52 and 62 days of age. Systolic blood pressure was measured in all animals and urinary corticosteroids in males. Compared with vehicle, the inhibitor lowered blood pressure at 50 days of age (when it could first be measured) until 64 days of age in females and 71 days of age in males. Corticosterone and aldosterone levels were not different between 19-AA- and vehicle-treated SS/Jr. 19-Nordeoxycorticosterone levels, however, were mildly reduced with the inhibitor (0.05 less than p less than 0.10). After 28 days of high salt diet all 23 of the 19-AA-treated SS/Jr were alive, whereas almost one half of the control animals had died. These data demonstrate that 19-AA attenuates the hypertension in SS/Jr; this effect may be through reduction in 19-nordeoxycorticosterone production.(ABSTRACT TRUNCATED AT 250 WORDS)