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1. Endothelium-derived substances are important regulators of the microcirculation. Endothelium-derived nitric oxide (NO), which is catalysed by nitric oxide synthase (NOS), is a potent modulator of vascular tone in the human ophthalmic artery, which is normally in a state of constant vasodilation due to the actions of NO. Endothelin-1 (ET-1) produces vasoconstriction of the anterior optic nerve vasculature and may be associated with glaucomatous optic neuropathy. The aetiology of primary open-angle glaucoma (POAG) remains largely unknown. Thus, alterations in the regulatory sequences of the genes coding for endothelium-derived NOS (eNOS) and ET-1 may have important effects in the development of POAG and were looked for in the present study. 2. In 56 patients with familial POAG and in 100 control subjects with no family history of hypertension or POAG, we examined the 5' flanking sequences of the eNOS and ET-1 genes, which contain many positive and negative regulatory regions affecting gene transcription, using polymerase chain reaction-based single strand conformation polymorphism analysis, to search for alterations. No variant in the promoter region of the ET-1 gene was observed in familial POAG or controls. Using three primer sets spanning 706 b.p. of the eNOS gene, we observed alterations in 11 of 56 (20%) familial POAG members and in seven of 100 (7%) controls. Sequence analysis demonstrated a C/T substitution at the 5' sequence position nucleotide (nt) -690 from the transcription start site, which lies between the cAMP regulatory element (nt -726 to -732) and an activator protein-1 binding domain (nt -655 to -661). 3. In summary, genotypic and allelic frequency analysis found no association between alterations in the promoter region of the ET-1 gene and familial POAG. A variant in the promoter region of the eNOS gene was seen in a significant percentage of familial POAG patients. Future expression studies will determine whether this polymorphism results in altered eNOS gene expression.

It is likely that abnormal baroreflex control mechanisms are at least partially responsible for autonomic dysfunction in chronic heart failure. We recently demonstrated that diastolic ventricular interaction is associated with impaired baroreflex control of vascular resistance in heart failure. We reasoned that by constraining left ventricular filling, such interaction would decrease baroreflex activity and, thereby, increase sympathetic and decrease parasympathetic outflow. We hypothesized, therefore, that diastolic ventricular interaction in chronic heart failure patients would be associated with autonomic dysfunction. We used radionuclide ventriculography to measure changes in left and right ventricular end-diastolic volumes during acute volume unloading achieved by -30 mm Hg lower-body negative pressure in 30 patients with chronic heart failure. An increase in left ventricular volume in association with a reduction in right ventricular volume indicates diastolic ventricular interaction (a larger increase indicating a greater degree of interaction). We also measured heart rate variability (n = 23) and resting venous plasma norepinephrine (n = 24), epinephrine (n = 24), and atrial natriuretic peptide (ANP) (n = 14). During lower-body negative pressure, while right ventricular volume decreased in all patients (P < 0.001), left ventricular end-diastolic volume increased (from 152 +/- 25 to 157 +/- 36 ml/m2, P = 0.01). The change in left ventricular volume was positively correlated with resting plasma norepinephrine (P < 0.01) and ANP (P < 0.005), and negatively correlated with the standard deviation of normal to normal R-R intervals (P < 0.005), the root-mean-square of differences between successive normal to normal R-R intervals (P < 0.05), total power (P < 0.01), low-frequency power (P < 0.01), and high-frequency power (P < 0.05). Diastolic ventricular interaction in patients with chronic heart failure is associated with sympathetic nervous system activation evidenced by increased plasma norepinephrine and reduced heart rate variability.

We compared the aldosterone-producing potency of the angiotensin II-sensitive wild-type aldosterone synthase genes and the ACTH-sensitive hybrid 11 beta-hydroxylase/aldosterone synthase gene by examining aldosterone, PRA, and cortisol day-curves (2-hourly levels over 24 h) in patients with familial hyperaldosteronism type I, before and during long-term (0.8-13.5 yr) glucocorticoid treatment. In 8 untreated patients, PRA levels were usually suppressed, and aldosterone correlated strongly with cortisol (r = 0.69-0.99). Fourteen studies were performed on 10 patients receiving glucocorticoid treatment that corrected hypertension, hypokalemia, and PRA suppression in all. ACTH was markedly and continuously suppressed in 6 studies, 3 of which demonstrated strong correlations between aldosterone and PRA (r = 0.77-0.92). ACTH was only partially suppressed in the remaining 8 studies; aldosterone correlated strongly: 1) with cortisol alone in 5 (r = 0.71-0.98); 2) with cortisol (r = 0.90) and PRA (r = 0.74) in one; 3) with PRA only in one (r = 0.80); and 4) with neither PRA nor cortisol in one. Unless ACTH is markedly and continuously suppressed, aldosterone is more responsive to ACTH than to renin/angiotensin II, despite the latter being unsuppressed. This is consistent with the hybrid gene being more powerfully expressed than the wild-type aldosterone synthase genes in familial hyperaldosteronism type I.

1. Familial primary open-angle glaucoma (POAG) is a heterogeneous disease of unknown aetiology and the elucidation of the underlying genetic mechanisms contributing to phenotypic expression will be essential if earlier diagnosis of at-risk individuals and more specific medical treatment can be achieved. In a significant percentage of patients with POAG, intraocular pressure increases in response to topical ocular glucocorticoids. 2. Atrial natriuretic peptide (ANP) assists in the regulation of intraocular pressure levels and binding of the glucocorticoid receptor dimer to the glucocorticoid-responsive element in intron 2 of the ANP gene has been shown to increase ANP mRNA levels in vitro. We amplified and examined this sequence in the ANP gene by PCR-SSCP analysis in 100 patients with familial POAG and in 60 normal control subjects. No base alterations in the amplified product were found. 3. Thus, the present study found no evidence for an alteration in the sequence of the glucocorticoid-responsive element of the ANP gene that could alter ANP gene transcription in patients with familial POAG. The mechanism responsible for the increase in intraocular pressure levels in response to glucocorticoids is most likely independent of the glucocorticoid-responsive element in the ANP gene.

The genetic mechanisms responsible for the formation of adrenocortical adenomas which autonomously produce aldosterone are largely unknown. The adrenal renin-angiotensin system has been implicated in the pathophysiology of these tumours. Angiotensin-converting enzyme (ACE) catalyses the generation of angiotensin II, and the insertion/deletion (I/D) polymorphism of the ACE gene regulates up to 50% of plasma and cellular ACE variability in humans. We therefore examined the genotypic and allelic frequency distributions of the ACE gene I/D polymorphism in 55 patients with aldosterone-producing adenoma, APA, (angiotensin-unresponsive APA n = 28, angiotensin-responsive APA n = 27), and 80 control subjects with no family history of hypertension. We also compared the ACE gene I/D polymorphism allelic pattern in matched tumour and peripheral blood DNA in the 55 patients with APA. The frequency of the D allele was 0.518 and 0.512 and the I allele was 0.482 and 0.488 in the APA and control subjects respectively. Genotypic and allelic frequency analysis found no significant differences between the groups. Examination of the matched tumour and peripheral blood DNA samples revealed the loss of the insertion allele in four of the 25 patients who were heterozygous for the ACE I/D genotype. The I/D polymorphism of the ACE gene does not appear to contribute to the biochemical and phenotypic characteristic of APA, however, the deletion of the insertion allele of the ACE gene I/D polymorphism in 16% of aldosterone-producing adenomas may represent the loss of a tumour suppressor gene/s or other genes on chromosome 17q which may contribute to tumorigenesis in APA.

Using the transperitoneal, laparoscopic approach, we performed 67 successful adrenalectomies between June 1993 and July 1995 at Greenslopes Hospital, Brisbane. There were 30 women and 37 men. Syndromes of primary adrenal hormone overproduction--primary aldosteronism (n = 52), pheochromocytoma (n = 6), and hypercortisolism (n = 1)--were present in 59 patients and apparently nonfunctioning adrenal tumors (of which one was malignant) in 8 patients. There was a significant difference in the time of operation between patients weighing < 80 kg and those weighing > 80 kg. Operations on males were slower than those on females, possibly explained by males being significantly heavier. Left-sided tumors outnumbered right-sided tumors; removal of right-sided adrenals took, on average, longer, but this difference was not significant.

Family history is a major risk factor in the development of primary open-angle glaucoma. The atrial natriuretic peptide system has been implicated in the underlying pathophysiology of the disease. This study looked for any alterations in the ANP gene and 5' proximal promoter regions of the ANP gene, in 53 patients from familial primary open-angle glaucoma families. The ANP gene was amplified by a long-PCR technique from peripheral blood DNA. Gross insertions or deletions in the gene were sought and allelic frequencies at two restriction fragment length polymorphism (RFLP) sites within the gene (Sca I, Hpa II) were compared with allelic frequencies obtained from 60 normal controls with no known family history of glaucoma or ocular hypertension. PCR-based single strand conformation polymorphism analysis was then used to search for possible point mutations in the 5' proximal promoter region of the ANP gene, which is known to contain regulatory elements which modify gene transcription. No gross alterations in the ANP gene or differences in allelic frequencies at the RFLP sites within the gene were observed. PCR-SSCP analysis of the 5' proximal promoter region of the gene revealed mutations in 10 patients in the -595 to -384bp region (19% of patients). Mutations in the 5' proximal promoter region of the ANP gene may contribute to altered ANP transcription in at least a proportion of patients with familial glaucoma.

1. In familial hyperaldosteronism type I (FH-I), expression of an adrenocorticotropic hormone (ACTH)-dependent hybrid 11 beta-hydroxylase/aldosterone synthase gene causes excessive 'hybrid steroid' (18-hydroxy- and 18-oxo-cortisol) production. In order to study the mechanism of elevated 'hybrid steroid' levels in angiotensin-unresponsive (AII-U) aldosterone-producing adenoma (APA), we compared responses of 24 h urinary 18-oxo-cortisol, aldosterone and cortisol to dexamethasone (0.5 mg q6h for 4 days) in 11 FH-I patients, 11 patients with AII-U APA, 11 patients with AII-responsive (AII-R) APA and 10 patients with bilateral adrenal hyperplasia (BAH). 2. Consistent, marked suppression (by at least 60%) of 18-oxo-cortisol levels by dexamethasone was seen in all groups except AII-U APA. Aldosterone levels were consistently suppressed to undetectable levels only in FH-I. Cortisol levels were suppressed to undetectable levels in all patients except two with AII-U APA. 3. Production of both 18-oxo-cortisol and aldosterone (and occasionally cortisol) in AII-U APA appears relatively ACTH-independent, consistent with a common mechanism involved in the formation of these two steroids from their respective precursors, which differs from that in FH-I. 4. In AII-R APA and BAH, 18-oxo-cortisol production appears markedly ACTH-dependent, but aldosterone production is not.

Aim: Since detection of familial hyperaldosteronism type I (glucocorticoid-suppressible hyperaldosteronism) allows specific treatment of hypertension with dexamethasone, we compared clinical, biochemical and genetic approaches to detection., Patients and Methods: We studied 22 affected patients, 21 from a single, large family and an additional adopted male. Plasma aldosterone, plasma renin activity and urinary 18-oxo-cortisol were measured by radioimmunoassay. The hybrid gene was demonstrated using either Southern blotting or a long polymerase chain reaction technique., Results: Thirteen out of 22 (59%) patients with familial hyperaldosteronism type I, but only four out of 12 (33%) under 20 years of age, were hypertensive. Plasma potassium and aldosterone were each normal in 20 out of 22 (91%), and unhelpful in diagnosis. Plasma renin activity, the aldosterone: plasma renin activity ratio and 18-oxo-cortisol were more sensitive, being abnormal in 20 out of 22 (91%), 19 out of 22 (86%) and 20 out of 20 (100%) patients, respectively. Aldosterone was unresponsive (<50% rise) to 2 h of upright posture following overnight recumbency in 15 out of 15 (100%) patients studied, and to angiotensin II infusion (2 ng/kg per min for 1 h) in 14 out of 14 patients (100%). Whereas all the abovementioned abnormalities are also characteristic of angiotensin II-unresponsive aldosterone-producing adenoma, marked aldosterone suppression following 4 days of dexamethasone (0.5 mg every 6 h) was sensitive and specific for familial hyperaldosteronism type I (n = 11). The hybrid gene was detectable in peripheral blood leucocyte DNA in all 22 affected patients by Southern blotting, and by a faster, long polymerase chain reaction method developed in our laboratory, both methods requiring only a single blood collection., Conclusions: Should studies in other families confirm its universal applicability, long polymerase chain reaction should prove to be the most practical means of detecting familial hyperaldosteronism type I in laboratories equipped with this technique.

Previous studies have shown a significant association between allelic frequencies at the ANP gene locus and aldosterone responsiveness to angiotensin in aldosterone-producing adenoma (APA). We searched for any gross insertions or deletions in the ANP gene in APA and any associations between allelic frequencies at the Hpa II and Sca I RFLP sites within the ANP gene and angiotensin-responsive and unresponsive APA and normal subjects. We also searched for possible point mutations in the promoter region of the ANP gene (-595 to transcription start site) in peripheral blood and tumor DNA from 59 patients with APA and in peripheral blood DNA from 39 normal subjects by polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) analysis. No large alterations in the ANP gene were observed, and no difference in allelic frequencies at the RFLP sites were seen between the two tumor subtypes, angiotensin-responsive and angiotensin-unresponsive APA, or between the APA group and normal subjects. SSCP analysis, however, did reveal mutations in the promoter region of the ANP gene (-375 to -595) in both peripheral blood and tumor DNA from 8 of 59 (14%) patients with APA, compared with only one of 39 normal controls (2.6%). This study suggests that alterations in the proximal promoter region of the ANP gene in APA may be important in the regulation of ANP transcription and may be involved in the underlying pathophysiology of aldosterone-producing adenoma in at least some patients.

We investigated renal and peripheral forearm extraction of atrial natriuretic peptide in patients with primary aldosteronism to determine whether alterations in extraction may contribute to the elevated levels of circulating atrial natriuretic peptide observed in primary aldosteronism. We obtained simultaneous venous blood samples from the left renal vein and a peripheral vein and from the radial artery in 28 patients with primary aldosteronism and 10 patients with essential hypertension. Renal extraction of atrial natriuretic peptide was significantly (P < .001) reduced (40 +/- 2%) in primary aldosteronism compared with essential hypertensive patients (62 +/- 3%). Peripheral forearm extraction was also reduced (P < .01) in primary aldosteronism compared with essential hypertensive patients (24 +/- 3% versus 38 +/- 4%). These findings are consistent with widespread downregulation of atrial natriuretic peptide receptors in primary aldosteronism. Consistent with reports that marked reduction in glomerular filtration rate is required before the renal extraction of atrial natriuretic peptide is reduced, no significant relationship between renal extraction of atrial natriuretic peptide and plasma creatinine was seen in primary aldosteronism or essential hypertension. Although the major regulators of atrial natriuretic peptide secretion in primary aldosteronism are presumably alterations in arterial blood pressure and plasma volume, reduced renal and peripheral extraction of atrial natriuretic peptide in primary aldosteronism may also contribute significantly to the elevated circulating levels observed.

The effects on blood pressure (BP) and heart rate (HR), at rest and during bicycle exercise, of the vascular selective calcium antagonist felodipine, the cardio-selective beta-blocker metoprolol, and of the two drugs in combination, were assessed in a double-blind, three-way cross-over study comprising 23 patients with essential, mild to moderate hypertension. All three treatment regimens were given to each patient in randomised order for 4 weeks after a 4 week placebo run-in period. Felodipine 10-20 mg daily, metoprolol 100-200 mg daily and the combination of felodipine 10-20 mg plus metoprolol 100 mg daily were all effective antihypertensive treatments both at rest and during exercise. The two drugs seemed to have additive effects and the effect on BP of the combination was greater than that of either drug given as monotherapy. The mean sitting BP was 148/103 mmHg at randomisation, after 4 weeks of placebo treatment, and 134/88, 134/94 and 121/84 mmHg, respectively, after 4 weeks' treatment with felodipine, metoprolol and the combination. Maximal exercise capacity was similar irrespective of treatment regimen, and the normal response to exercise BP and HR was maintained during all active treatments. Changes observed in volume regulatory hormones (PRA, aldosterone and ANP) were consistent with a direct tubular natriuretic-diuretic effect of felodipine and of beta-blocker attenuated release of renin. All treatment regimens were well tolerated and adverse events reported were usually mild and transient.

1. In patients with primary aldosteronism due to angiotensin-responsive and angiotensin-unresponsive aldosterone-producing adenomas, no differences in the coding region of the angiotensin II type 1 (AT1) receptor gene were observed compared to normal subjects in peripheral blood leucocyte DNA. 2. Furthermore, no differences in the AT1 receptor gene were observed in DNA extracted from tumour tissue of either subgroup. 3. Genotypic and allelic frequencies for an RFLP detected in the coding region of the AT1 receptor gene were not significantly different between normal subjects and patients with aldosterone-producing adenomas as a group, nor between normal subjects and patients of either subgroup when compared with each other. 4. In those patients heterozygous in peripheral blood at the RFLP site, tumour DNA showed the same allelic pattern. 5. In patients with aldosterone-producing adenomas either responsive or unresponsive to the renin-angiotensin system, no differences were detected using SSCP analysis in the coding region of the AT1 receptor gene in peripheral blood or tumour tissue.

1. Early diagnosis of Familial Hyperaldosteronism Type I (FH-I, glucocorticoid-suppressible hyperaldosteronism) in asymptomatic, affected individuals is essential if death from stroke is to be prevented. 2. In 21 patients with FH-I (presence of the causative hybrid 11 beta-hydroxylase/aldosterone synthase gene confirmed by Southern blot testing), various biochemical parameters were compared as possible screening tests. Hypokalaemia and elevated plasma aldosterone each detected only two (10%) of the affected individuals. 3. Plasma renin activity 19 (90%) and aldosterone/renin ratio 18 (86%) were more reliable but not free from false negatives. 4. Levels of the urinary 'hybrid' steroid, 18-oxocortisol, were elevated (P < 0.01) in all 15 patients tested (138.2 +/- 17.4 micrograms/g creatinine, range 41.6 +/- 281.0 micrograms/g) with no overlap when compared with 11 normals (9.7 +/- 1.3 micrograms/g, range 2.8-17.4 micrograms/g). 5. We conclude that measurement of urinary 'hybrid' steroids is probably the most rapid and reliable biochemical screening test currently available for FH-I, with confirmation dependent on demonstration of the hybrid gene by genetic techniques.

1. Aldosterone responsiveness to ACTH was compared in eleven patients with angiotensin-unresponsive (AII-U) aldosterone-producing adenomas (APA), 16 with AII-responsive (AII-R) APA and 19 with bilateral adrenal hyperplasia (BAH). 2. After overnight recumbency, aldosterone levels were highest in AII-U APA and lowest in BAH. Following 2 h of upright posture, however, levels were similar among the three groups. 3. During ACTH infusion, aldosterone levels in AII-U and AII-R APA were similar, and higher than those in BAH. Because of the higher basal level, the percentage rise in aldosterone was lower in AII-U APA compared with the other groups, as was the ratio of per cent aldosterone rise to per cent cortisol rise. 4. Slightly but significantly reduced plasma cortisol levels observed in the AII-R APA group may reflect secretion by AII-R APA of a cortisol-like substance that is capable of suppressing ACTH and thus adrenal cortisol production. 5. The tendency of aldosterone to follow the diurnal rhythm of ACTH in AII-U APA may thus represent an unmasking of the normal ability of ACTH to regulate aldosterone, secondary to the loss of AII responsiveness, rather than an enhancement of ACTH effect.

1. In a 19 month period from June 1993 to December 1994, 60 patients (mean age 54.8 +/- 1.5 years s.e.m.; 32 males, 28 females) underwent unilateral laparoscopic adrenalectomy by one of us (JCR) for the treatment of hypertension due to primary aldosteronism (n = 48), phaeochromocytoma (n = 3) and cortisol-producing adenoma (n = 1) or to remove adrenal massess incidentally discovered on abdominal computerized tomography scanning ('incidentaloma') performed for other reasons (seven adenomas without biochemical evidence of excessive steroid hormone or catecholamine secretion and one carcinoma autonomously producing cortisol). 2. Compared with conventional open procedures, laparoscopic adrenalectomy was associated with reduced recovery time and a low complication rate (one pulmonary embolus and one port site incisional hernia). 3. Operation time with experience approximates that of open procedures (60 min), but is significantly longer in obese than in non-obese patients, and in males than in females. 4. Patients with adrenal causes of hypertension were cured or significantly improved by laparoscopic unilateral adrenalectomy. 5. Because of our concern regarding malignant potential of incidentalomas and high patient acceptance of laparoscopic techniques, we have reduced our size criteria for removal of incidentalomas.

1. Angiotensin-responsive aldosterone-producing adenomas (AII-R-APA) have increased expression of renin mRNA compared with angiotensin-unresponsive aldosterone-producing adenomas (AII-U-APA) or normal adrenals. 2. Further, significant associations between the BglI, TaqI and HinfI RFLP and aldosterone responsiveness to the renin-angiotensin system of the two subgroups of patients have been reported. 3. Using the polymerase chain reaction based technique single stranded conformational polymorphism, we detected no alterations in exon 1 of the renin gene in peripheral blood leucocyte DNA from normal AII-U-APA and AII-R-APA subjects. 4. Using long-PCR, we amplified a fragment of the renin gene consisting of a region covering 500 bp upstream of exon 1, exon 1 and intron A. No gross changes in this area of the renin gene were found in the three groups of subjects studied. However this does not exclude small alterations in this area.

In Familial Hyperaldosteronism Type I (FH-I, glucocorticoid-suppressible hyperaldosteronism), a curable form of hypertension inherited in an autosomal dominant fashion, the underlying genetic defect is a "hybrid gene" in which 11 beta-hydroxylase gene regulatory elements are fused to the coding region of the aldosterone synthase gene. The detection of this hybrid gene by Southern blotting is time consuming and involves the use of radioactive isotopes. We describe a new, long polymerase chain reaction-based method for detecting the hybrid gene which greatly reduces the time required to obtain a result, avoids exposure of laboratory workers to radioactive materials, and will thereby facilitate the screening of patients for the presence of FH-I.

Primary aldosteronism is the commonest cause of potentially curable hypertension when diagnosed in both florid and less florid forms. Genetic screening, so far available only for glucocorticoid-suppressible hyperaldosteronism, permits diagnosis from birth, before any biochemical or clinical abnormalities appear. Biochemical screening using the aldosterone-to-renin ratio permits diagnosis in the absence of raised aldosterone or of hypokalemia. Primary aldosteronism occurs in several familial forms. As well as the variety described in 1966 which is ACTH-dependent and glucocorticoid-suppressible, and not so far associated with tumors, another variety described in 1991 is not glucocorticoid-suppressible and is frequently associated with aldosterone-producing adenomas (APAs). Primary aldosteronism due to adrenocortical hyperplasia, adenoma, or carcinoma can also occur as part of the multiple endocrine neoplasia syndromes, where normoplasia, hyperplasia, benign neoplasia, and malignant neoplasia can exist in the same patient in the same endocrine gland(s) at the same time. The morphology of adrenocortical hyperplasia causing primary aldosteronism ranges from glomerulosa-like (idiopathic hyperplasia of the adrenals) to fasciculata-like (glucocorticoid-suppressible hyperaldosteronism). The morphology of adrenocortical neoplasia causing primary aldosteronism can also be either predominantly glomerulosa-like or fasciculata-like, in our experience equally often. Varying morphology of APAs is associated with varying responses of aldosterone to angiotensin II. Tumors predominantly fasciculata-like are unresponsive to angiotensin II, whereas those predominantly glomerulosa-like are responsive to angiotensin II. Both subtypes can be seen in a single family. Primary aldosteronism represents a spectrum of genetic disorders resulting in hyperplasia or neoplasia, but all are associated with some degree of autonomy of aldosterone production, independent of the renin-angiotensin system.

Approximately one half of the aldosterone-producing adenomas (APA) removed from patients with primary aldosteronism in the Hypertension Unit at Greenslopes Hospital belong to a subgroup in which aldosterone levels are responsive to the renin-angiotensin system (angiotensin-responsive APA; AII-R-APA), unlike classical APAs in which aldosterone is unresponsive (AII-U-APA). Renin mRNA levels in AII-R-APA were elevated when compared with those in AII-U-APA or normal adrenal cortices. Renin mRNA levels in some adrenal cortices surrounding AII-R-APA (but never in AII-U-APA) were raised, suggesting that a genetic defect is not confined to the tumor. Renin gene RFLP analysis in peripheral blood DNA revealed a significant difference in allelic frequencies between patients with AII-R-APA and AII-U-APA, suggesting an association between an alteration in the renin gene and aldosterone responsiveness to the renin-angiotensin system in patients with APAs.

Primary aldosteronism is an important, potentially curable, form of hypertension. We examined the possible association between restriction fragment length polymorphisms in the atrial natriuretic peptide (ANP) gene and responsiveness of aldosterone to angiotensin II in 59 patients with primary aldosteronism due to aldosterone-producing adenoma (APA). Significant differences in the allelic frequencies of the BglI, TaqI and XhoI polymorphic sites at the ANP gene locus (chromosome 1; 1p36) between angiotensin II-unresponsive and angiotensin II-responsive tumors were observed. Variation in the ANP gene between the two groups may result in altered expression of ANP within the adrenal gland, and may contribute to the biochemical regulation of aldosterone production of these two subgroups of patients with APA.

1. In 1991 we described a familial variety of primary hyperaldosteronism which was not glucocorticoid-suppressible and was associated with adenoma formation, and called it familial hyperaldosteronism type II (FH-II) in order to distinguish it from the glucocorticoid-suppressible variety described in 1966, familial hyperaldosteronism type I (FH-I). 2. In 1992 the genetic basis of FH-I was clarified by description of a hybrid gene. 3. Primary aldosteronism due to bilateral adrenocortical hyperplasia or to aldosterone-producing tumour can be part of the multiple endocrine neoplasia type I syndrome (MEN I), in which loss of heterozygosity has been described on chromosome 11q13. Loss of heterozygosity at the MEN I locus was found in five of 26 aldosterone-producing tumours from our series (by Japanese collaborators). These included two with adrenal cancer and two with FH-II. 4. We recently described an association of aldosterone responsiveness of aldosterone-producing adenomas with renin gene restriction fragment length polymorphisms, suggesting a possible role for renin genotype and intra-adrenal renin gene expression in the development and biochemical expression of some aldosterone-producing tumours. 5. We found abnormal karyotypes in 13 of 32 benign aldosterone-producing adenomas.

1. Normokalaemic primary aldosteronism (PA) masquerades as 'essential hypertension', and 50% of patients with aldosterone-producing adenoma (APA) are normokalaemic at presentation to this unit. 2. Angiotensin-responsive (AII-R) APA is as common as angiotensin-unresponsive (AII-U) APA, and requires adrenal venous sampling for differentiation from bilateral adrenal hyperplasia (BAH). 3. From 1981 to 1992, 55 patients with APA underwent unilateral adrenalectomy and were followed up for at least 12 months postoperatively. Hypertension was cured in 55% and improved in the remainder. 4. Cure rate was lower (P < 0.001) in males (11/32, 34%) vs females (19/23, 83%), lower (P < 0.005) in patients over 45 years of age (13/33, 39%) vs those 45 years or younger (17/22, 77%), lower (P < 0.05) in AII-R APA (11/28, 39%) vs AII-U APA (19/27, 70%) and tended to be lower (not significant) in normokalaemic APA (7/17, 41%) vs hypokalaemic APA (23/38, 61%). 5. A higher proportion (P <0.001) of AII-R APA patients were males (23/28, 82%) vs AII-U APA (9/27, 33%), and a higher proportion were from the older age group AII-U APA 13/27, 48%; P < 0.05). Females with AII-U APA who were hypokalaemic had a very high cure rate (16/17, 94%). 6. Since unilateral adrenalectomy cures or improves blood pressure in normokalaemic and AII-R as well as in hypokalaemic and AII-U patients, all hypertensives should be screened for PA, and AII-R APA differentiated from BAH in proven PA.

1. This study sought to assess the incidence of primary aldosteronism in 199 hypertensives who were normokalaemic and in whom the question of primary aldosteronism had never been raised. 2. The screening test applied was the aldosterone to renin ratio in plasma, which was raised in 40 and normal in 159 patients. A second ratio was normal in 14 of these 40. 3. Twenty-two patients with two further raised ratios required fludrocortisone suppression testing. This has been completed in 17, and failure to suppress led to a diagnosis of primary aldosteronism in all. 4. A dexamethasone suppression test (DST) excluded ACTH-dependent hyperaldosteronism and laterality of aldosterone production was determined by adrenal vein sampling. 5. Unilaterality in five patients led to adrenalectomy in four and spironolactone in one. Bilaterality in six patients led to spironolactone. 6. This study so far provides a proven (minimum) incidence for primary aldosteronism of 8.5%, a probable incidence of 12.0% (including two raised ratios) and a possible (maximum) incidence of 13.0% (leaving out those with second ratio normal). Exclusion of hypokalaemic hypertensives will lead to an underestimation of the true incidence of primary aldosteronism. 7. Based on this and other evidence, it is estimated that the incidence of primary aldosteronism in the 'essential hypertensive' population is between 5 and 15%, and is probably around 10%.

1. Two patients with adrenaline-only secreting phaeochromocytomas and primary aldosteronism were studied. 2. Urinary adrenaline levels were raised and plasma adrenaline was not suppressed normally following administration of clonidine. Plasma aldosterone to plasma renin activity ratios were repeatedly elevated. 3. Both had large intra-adrenal phaeochromocytomas visible on computerized tomography (CT) scanning. Surrounding adrenal cortical tissue contained an adenoma in one and nodular hyperplasia in the other. 4. Following removal of the adrenal gland containing the phaeochromocytoma, plasma and urinary adrenaline levels, and plasma aldosterone to plasma renin activity ratios returned to normal. 5. Adrenaline-only secreting phaeochromocytomas and primary aldosteronism have been rarely diagnosed even as separate entities, but reliable screening tests are now available. 6. Simultaneous presence of these two conditions of hormone excess is probably a chance occurrence. Alternatively, there may be a genetic predisposition to endocrine dysplasia, or an interaction between the contiguous medullary and cortical tissues, particularly after the normal architecture has been disturbed by an enlarging phaeochromocytoma.

1. Aldosterone levels in patients with unilateral aldosterone-producing adenomas may be responsive or unresponsive to the renin-angiotensin system, with the former often previously misdiagnosed as bilateral adrenal hyperplasia. 2. In tumours from patients in the responsive subgroup, renin mRNA is expressed in greater amounts than in tumours from patients in the unresponsive subgroup, or in normal adrenals. 3. We compared the frequency of four renin gene polymorphisms in peripheral blood DNA from the two subgroups and found significant associations between BglI, TaqI and HinfI restriction fragment length polymorphisms (RFLP) and aldosterone responsiveness. 4. Allelic variation in the constitutive renin gene was associated with a specific cause of hypertension.

1. Elevated peripheral atrial natriuretic peptide (ANP) levels were observed in 12 patients with unilateral renal artery stenosis (U-RAS). 2. Renal extraction of ANP was higher across the affected than the unaffected kidney in U-RAS, provided the glomerular filtration rate in the affected kidney was not severely reduced (> 12 mL/min). As ANP is a high clearance compound, reduced flow on the affected side may result in increased renal extraction of ANP. 3. When glomerular filtration rate (GFR) in the affected kidney was severely reduced (< 12 mL/min), renal extraction of ANP was also reduced, possibly contributing to increased circulating ANP levels in this subgroup. 4. Overall, renal extraction of ANP was inversely correlated to peripheral ANP levels in patients with U-RAS. This might be explained by progressive sodium retention as GFR falls leading to volume expansion and increased ANP secretion.

Aldosterone-producing adenomas may be responsive or unresponsive to the renin-angiotensin system. In tumours from patients in the responsive subgroup, renin mRNA is expressed in greater amounts than in tumours from patients in the unresponsive subgroup, or in normal adrenals. We compared the frequency of two renin gene polymorphisms in peripheral blood DNA from the two subgroups and found a significant association (allele frequency X2 = 7.67, p < 0.006) between BglI polymorphism and aldosterone responsiveness. This may be a significant determinant of the biochemical behaviour of these tumours.

The responses of renin, aldosterone, and blood pressure to ACTH suppression with dexamethasone in a 61-yr-old man with glucocorticoid-suppressible hyperaldosteronism were modified by coexistent atheromatous renal artery stenosis (RAS). The apparent responsiveness of aldosterone to angiotensin-II resulting from RAS has implications for the regulation of steroidogenesis in this condition. After successful surgical correction of the RAS, the response changed and resembled that seen in two younger males (one his son) with uncomplicated glucocorticoid-suppressible hyperaldosteronism.

Because familial hyperaldosteronism type II (FH-II) includes tumor formation, we examined the karyotypes of benign adrenocortical aldosterone-producing adenomas (APAs), including those from patients with FH-II. Cell culture was successful in 12 of 14 tumors removed, two of which were from patients with FH-II. Five of the 12 tumors cultured (one from a patient with FH-II) had abnormal karyotypes. All were from male patients, and loss of the Y chromosome was observed in each. One showed loss of chromosome 19, and another showed an unbalanced t(6;7) producing partial trisomy 7q. Oncogenes are present at these breakpoints, and loss of the Y chromosome and monosomy 19 have previously been reported in neoplasia. This is the first report of cytogenetic abnormalities in benign adrenocortical tumors.

1. Six (12%) out of 52 respondents to newspaper advertisements for antihypertensive drug trials had elevated aldosterone to renin ratio, confirmed by repeated measurement. 2. Failure to suppress aldosterone with fludrocortisone acetate administration and oral salt loading confirmed the presence of primary aldosteronism in all six patients. 3. Two of the six patients have already had aldosterone-producing adenomas removed, one has commenced spironolactone, and one has an adrenal mass on computerized tomography but investigation is incomplete. 4. None of the six patients with primary aldosteronism had unprovoked hypokalaemia. 5. Plasma aldosterone levels did not distinguish those patients with subsequently proven primary aldosteronism from the others. Plasma renin activity (PRA) was a better discriminator, but not as good as the aldosterone to renin ratio. 6. The incidence of primary aldosteronism is probably much higher than the 1% currently quoted in texts, with earlier, normokalaemic forms accounting for the majority of cases.

1. Infusion of increasing doses of angiotensin II (AII) in normal subjects sequentially increased blood pressure, aldosterone and atrial natriuretic peptide (ANP) levels. 2. The slope of ANP response to AII was positively correlated with basal ANP and with the slope of blood pressure response to AII (pressor slope) but not with age. 3. This is consistent with the response of ANP to AII being mediated partly by the rise in blood pressure, independent of ageing. 4. As expected in a selected normotensive population, there was no correlation between basal blood pressure and age, but pressor slope was positively correlated with age. 5. Thus, dose-response relationships may be an index of age-induced alterations in pressure regulatory mechanisms.

1. Nineteen out of 47 patients (40%) with confirmed unilateral aldosterone-producing adenoma (APA) were responsive to low-dose angiotensin II infusion (AII-R), as defined by an increase in plasma aldosterone concentration of > 50% over basal at 2 ng/kg per min for 60 min. 2. Seven to ten days after unilateral adrenalectomy, aldosterone was no longer responsive to angiotensin infusion in AII-R APA (100%, n = 17). Therefore, angiotensin responsiveness resides within the adenoma in AII-R APA. 3. The upright posture test for the differentiation of adenoma from hyperplasia was unreliable for the AII-R APA (26%), but generally reliable in the angiotensin-unresponsive subtype, (AII-U APA, 96%). 4. The reported predominance of females in APA was seen in AII-U APA (68%), but was reversed in AII-R APA (37%).

1. In vitro short-term production of cortisol by dispersed tumour and non-tumourous adrenal cortical cells was measured with and without added angiotensin II (AII) or adrenocorticotrophin (ACTH) in adrenals removed from five patients with primary aldosteronism. 2. Aldosterone-producing adenomas (APA) were classified as angiotensin responsive (AII-R) or angiotensin unresponsive (AII-U) based on pre-operative behaviour in vivo. 3. Cortisol was produced by both tumour and cortex in vitro without stimulation, and significantly more cortisol was generated by the cortex. 4. Addition of AII significantly increased cortisol production by both tumour and cortex to an equal extent. 5. Addition of ACTH also significantly increased cortisol production by both tumour and cortex, but tumours were more responsive than cortex. The response to ACTH exceeded the response to angiotensin in both tumour and cortex. 6. There was no obvious difference between AII-R and AII-U APA in terms of cortisol production.

The levels of plasma atrial natriuretic peptide in response to graded adrenaline infusion were determined in six patients with essential hypertension and six healthy normotensive subjects (controls). Basal plasma adrenaline concentration was similar in both groups and rose progressively and to a similar level during adrenaline infusion. Plasma noradrenaline rose in both groups and to the same extent during the 26 and 39 ng/kg/min adrenaline infusion rates. Basal plasma atrial natriuretic peptide levels were higher in the hypertensives than in the controls. Graded adrenaline infusion had no effect on atrial natriuretic peptide levels in the controls but significantly raised atrial natriuretic peptide levels in the hypertensives. Systolic blood pressure rose progressively during adrenaline infusion at a lower infusion rate in the hypertensives than in the controls. Similarly, while heart rate rose during adrenaline infusion in both groups, there was a greater rise in the hypertensives. The increased cardiovascular responsiveness to adrenaline infusion in patients with essential hypertension may explain why plasma atrial natriuretic peptide levels rose only in this group and not the normotensive subjects.

Exciting developments in knowledge of primary aldosteronism include description of new subtypes and elucidation of the genetic basis of one variety. Furthermore, relatively simple biochemical screening (aldosterone/renin ratio) has disclosed that primary aldosteronism is more common than previously thought, by diagnosing patients at an earlier, normokalaemic stage. The mutant gene discovered in the glucocorticoid-suppressible variety (FHI) codes for an aldosterone biosynythetic enzyme normally controlled by angiotensin II, and now controlled by corticotropin. The zona fasciculata is hyperplastic and makes aldosterone and "hybrid steroids" 18-oxocortisol and 18-hydroxycortisol in excess, in response to ACTH but not to angiotensin II. Adrenal tumours have not yet been described in this condition. Aldosterone-producing adenomas (Conn's syndrome) are also commonly composed of zona fasciculata-like cells, make "hybrid steroids" in excess and are very sensitive to ACTH but not to angiotensin II. We have described a new variety of aldosterone-producing adenoma which is responsive to angiotensin II (AII-responsive APA), consists of at least 20% zona glomerulosa-like cells, and does not make "hybrid steroids" in excess. We have also described a new familial variety of primary aldosteronism that includes tumours and is not glucocorticoid-suppressible (FHII). We propose that primary aldosteronism is a spectrum of genetic diseases expressed as either hyperplasia or neoplasia, and that morphological and genetic diversity explains biochemical and clinical behaviour.

1. Overnight recumbent and upright plasma atrial natriuretic peptide (ANP) levels were markedly elevated (P less than 0.001) in patients with orthostatic hypotension (OH). 2. Overnight urinary clearance of ANP was significantly lower (P less than 0.01) in patients with OH, and was inversely correlated with plasma ANP levels (r = -0.94, P less than 0.01). The same negative correlation (r = -0.87, P less than 0.01) was seen in normal subjects. 3. Reduced urinary clearance of ANP may be associated with reduced filtered load and increased binding of ANP to the neutral endopeptidase 24.11 receptor binding sites in the proximal renal tubule. 4. ANP may be involved in the pathophysiology of orthostatic hypotension.

1. Two hours after a single dose of indomethacin (INDO), plasma renin activity (PRA) and atrial natriuretic peptide (ANP) levels decreased, which is consistent with an effect of lowering prostaglandins (PG). 2. After 48 h of INDO, PRA remained low but ANP had increased, which is consistent with the known effect of prostaglandin inhibitors to cause sodium retention, with a resulting volume expansion. 3. Infusions of angiotension II (AII), which raises diastolic blood pressure (BP) 20 mmHg or more, consistently raised ANP levels. The ANP response to AII infusion was reduced 48 h after INDO, which is consistent with an important role for PG in AII-stimulated ANP release. 4. After PG were blocked with INDO, the stimulating effect of AII on ANP at doses that increased diastolic BP less than 20 mmHg was insignificant, whereas before INDO it was significant. 5. In dose-response studies, INDO increased the systolic BP response but decreased the ANP response to AII, which is consistent with a direct effect of PG on ANP that is independent of systolic BP. 6. Prostaglandins and BP are important in the ANP response to AII infusion in normal subjects, but AII itself appears to have little direct effect on ANP.

1. Subpressor calcium infusion for 1 h, which raised calcium levels to the upper limit of normal in normal subjects, increased plasma and urinary levels of atrial natriuretic peptide (ANP). 2. Heart rate fell, presumably due to carotid baroreflex stimulation (supported by the fall in noradrenaline) and the resultant fall in cardiac output prevented the expected rise in blood pressure due to the rise in total peripheral resistance (TPR). Thus the increase in ANP was not explained by an increase in blood pressure or noradrenaline. 3. There was no evidence for increased atrial stretch (no increase in atrial area or early velocity of left ventricular filling) as a mechanism for increased ANP. 4. Isovolumic left ventricular relaxation time increased, early velocity of ventricular filling decreased and TPR increased, consistent with increased tone in left ventricular and arteriolar muscle. 5. This suggests a direct effect of calcium on the atrial myocyte, stimulating ANP either through contractile or secretory mechanisms.

1. Thirteen patients from five families had Familial Hyperaldosteronism Type II (FH-II), a new variety of familial primary aldosteronism not suppressible with dexamethasone that often involves adrenocortical adenoma formation. 2. Five patients had solitary aldosterone-producing adenomas, three had bilateral autonomous overproduction of aldosterone, and in five the subtype is yet to be determined. 3. Comparing FH-II patients with 88 patients with primary aldosteronism of other causes revealed no differences in mean age at presentation or at onset of hypertension, sex incidence, lowest recorded serum potassium, plasma aldosterone, plasma renin activity or adenoma size. 4. Analysis of DNA in peripheral blood of patients with FH-II, their affected and unaffected relatives, and in removed tumours is in progress in order to determine the underlying genetic defect(s) in FH-II, perhaps an abnormality in the P-450aldo gene (CYP11B2). 5. It is recommended that hypertensive relatives of patients with primary aldosteronism should have measurements of the aldosterone/renin ratio.

The syndrome of hypertension and hyperkalemia, hyperchloremic acidosis with normal glomerular filtration rate (Gordon's syndrome) is characterised by volume expansion, suppressed renin and reduced mineralocorticoid-induced renal clearance of potassium. The clinical and biochemical defects are aggravated by high salt diet and corrected by low salt diet, leading to the hypothesis of excessive sodium reabsorption in the nephron proximal to where aldosterone acts. In this study, we used lithium clearance as a marker of proximal sodium reabsorption in three patients with Gordon's syndrome, in order to further localise the site in the nephron of defective sodium handling. Fractional excretion of lithium was decreased, and absolute and fractional proximal reabsorption of sodium was increased compared to normal controls. In addition, absolute distal reabsorption of sodium was decreased, consistent with decreased mineralocorticoid activity. Fractional excretion of potassium was markedly decreased and did not rise with increased distal delivery of sodium during saline infusion. However, after severe dietary sodium restriction had elevated plasma aldosterone (lowering plasma potassium levels to normal), fractional excretion of potassium was raised by saline infusion. Reduced lithium clearance in patients with Gordon's syndrome supports the hypothesis of increased proximal sodium reabsorption in this condition.

1. Plasma atrial natriuretic peptide (ANP), renin activity, aldosterone, sodium, potassium and serum total protein and albumin during and after 14 normal pregnancies were compared with age-matched controls. 2. None developed toxaemia and all delivered healthy babies. 3. During pregnancy, plasma renin activity and aldosterone were significantly (P less than 0.01) higher and potassium, total protein and albumin significantly lowew (P less than 0.01) than in controls, while ANP was not different from the control level. 4. At 6-13 weeks postpartum, a significant (P less than 0.01) suppression of renin and aldosterone was accompanied by significant (P less than 0.01) elevation of atrial natriuretic peptide when compared with controls. 5. The hormonal changes are consistent with 'effective plasma volume' reduction during pregnancy and persistent volume expansion after pregnancy, perhaps due to a renal glomerular lesion sustained late in pregnancy. In contrast, levels of potassium, total protein and albumin are consistent with haemodilution during pregnancy and its correction postpartum. 6. Measurements available in seven women 40-120 weeks postpartum showed normal renin and aldosterone levels in most, but ANP was still elevated. 7. Pregnancy may have a protracted effect on volume regulation.