Interrelations between age and plasma renin, aldosterone and cortisol, urinary catecholamines, and the body sodium/volume state in normal man

Confounders of the aldosterone-to-renin ratio when used as a screening test in hypertensive patients: A critical analysis of the literature

The aldosterone‐to‐renin ratio (ARR) is a common screening test for primary aldosteronism in hypertensives. However, there are many factors which could confound the ARR test result and reduce the accuracy of this test. The present review's objective is to identify these factors and to describe to what extent they affect the ARR. Our analysis revealed that sex, age, posture, and sodium‐intake influence the ARR, whereas assay techniques do not. Race and body mass index have an uncertain effect on the ARR. We conclude that several factors can affect the ARR. Not taking these factors into account could lead to misinterpretation of the ARR.

Effects of Moderate Combined Resistance- and Aerobic-Exercise for 12 Weeks on Body Composition, Cardiometabolic Risk Factors, Blood Pressure, Arterial Stiffness, and Physical Functions, among Obese Older Men: A Pilot Study

We demonstrated the hypothesis that combined exercise improves body composition, cardiometabolic risk factors, blood pressure (BP), arterial stiffness, and physical functions, in obese older men. Older men (n = 20) were randomly assigned to combined exercise training (EXP; n = 10) or control groups (CON; n = 10). The combined exercise was comprised of elastic-band resistance training and walking/running on a treadmill and bicycle at 60–70% of maximal heart rate for 3 days/weeks. EXP showed significant decreases in body weight, body mass index, and %body fat (p < 0.05). The exercise program significantly reduced BP, mean arterial pressure, pulse pressure, and brachial-ankle pulse wave velocity. Furthermore, while the plasma levels of low-density lipoprotein cholesterol and epinephrine were significantly reduced in EXP, VO₂ peak and grip strength were significantly enhanced (p < 0.05). In conclusion, it is indicated that 12-week regular combined exercise improves body composition, cardiometabolic risk factors, hemodynamics, and physical performance in obese older men.

Sex differences in transcriptomic profiles in aged kidney cells of renin lineage

Renin expressing cells in the kidney’s juxta-glomeruluar compartment likely also serve as progenitors for adult glomerular cells in disease. Although these cells of renin lineage (CoRL) decrease in number with advancing kidney age, accompanied by less responsiveness to typical stimuli such as ACE-inhibition, mechanisms and the impact of sex as a biological variable with age are not known. Accordingly, labeled CoRL were sorted from individual young (2m) and aged (27m) male and female Ren1cCre|ZsGreen reporter mice, and their transcriptomic profiles analyzed by RNA seq. When both aged female and male mice were combined, there were 48 differentially expressed genes (DEG) compared to young mice. However, when compared to their young sex-matched mice, aged female and male mice had 159 and 503 DEGs respectively. In addition to marked differences in individual genes between aged female and male mice, gene ontology analysis showed major pathway differences by sex. The majority of DEGs in one sex did not significantly change or changed in the opposite direction in the other sex. These results show that in CoRL of advanced age, individual genes and gene ontologies change, but differ between female and male mice, highlighting sex related differences the aging process.

The aldosterone to renin ratio in the diagnosis of primary aldosteronism: Promises and challenges

The complexity of evaluating patients for secondary treatable causes of hypertension is underappreciated. Primary aldosteronism (PA) is the most prevalent cause of secondary hypertension (3%-32% of hypertensive patients). The recent endocrine society clinical practice guideline (ESCPG), "The Management of Primary Aldosteronism: Case Detection, Diagnosis, and Treatment", differs from the previous version in the explicit recognition of PA as a major public health issue. Despite this, PA is underdiagnosed. The guidelines call on physicians to substantially ramp up the screening of hypertensive patients at risk of PA. Further, it recommends the plasma aldosterone to renin ratio (ARR), as the test of choice for screening for PA. However, the ARR is a highly variable test with reported diagnostic sensitivities and specificities ranging from 66% to 100% and 61% to 100%, respectively. Variability of the ARR can be attributed to the high degree of within-subject variation, differences in sampling protocols, laboratory assays, reporting units, the effect of medications and the population characteristics used to establish the decision thresholds. These factors render the possibility of false positive and false negative results-which have the potential to adversely impact patients. The limitations and caveats to the use of the ARR necessitate an effective clinic-laboratory interface, with specialist physician and clinical scientist collaboration for ARR result interpretation. Improvement in the diagnostic sensitivity and specificity of the ARR is predicated on harmonisation of pretesting patient preparation criteria, knowledge of the analytical methods used to derive the ratio and the method-specific threshold for PA.

Effects of full-fat dairy products on subclinical vascular function in adults with elevated blood pressure: a randomized clinical trial

BACKGROUND

High consumption of low- and non-fat dairy products improves vascular dysfunction associated with elevated arterial blood pressure (BP). Currently, it is unknown if conventional full-fat dairy products improve vascular functions.

OBJECTIVES

To determine if adding whole milk and full-fat dairy products to the normal routine diet improves vascular function in adults with elevated BP.

DESIGN

Sixty adults (age ± SEM; 58 ± 2 years) with elevated BP (systolic/diastolic; 120-159/ < 99 mmHg) were randomized into a controlled crossover intervention trial consisting of two 4-week dietary periods. The high dairy condition consisted of adding four daily servings of whole milk or full-fat dairy products to the normal diet and eliminated all dairy intake during the control (no dairy) condition. A 2-week washout period separated the dietary conditions.

RESULTS

Carotid-femoral pulse wave velocity (cfPWV) did not differ significantly between high dairy (11.3 ± 0.3 versus 10.9 ± 0.3 m/sec) and no dairy conditions (11.2 ± 0.3 versus 11.0 ± 0.3 m/sec). The results were consistent when ultrasound-derived vascular distension measures (arterial compliance, beta-stiffness index, and elastic modulus) were evaluated. Cardiovagal baroreceptor sensitivity (via Valsalva maneuver) demonstrated no significant difference for either dietary condition. Brachial arterial flow-mediated dilation (FMD) did not differ significantly during the high dairy (5.7 ± 0.5 versus 5.4 ± 0.6%) and no dairy conditions (6.5 ± 0.5 versus 5.6 ± 0.6%).

CONCLUSIONS

The solitary addition of whole milk and full-fat dairy products has no effect on subclinical vascular function in adults with elevated BP.

Lineage tracing aged mouse kidneys shows lower number of cells of renin lineage and reduced responsiveness to RAAS inhibition

Blocking the renin-angiotensin-aldosterone system (RAAS) remains a mainstay of therapy in hypertension and glomerular diseases. With the population aging, our understanding of renin-producing cells in kidneys with advanced age is more critical than ever. Accordingly, we administered tamoxifen to Ren1cCreERxRs-tdTomato-R mice to permanently fate map cells of renin lineage (CoRL). The number of Td-tomato-labeled CoRL decreased significantly in aged mice (24 mo of age) compared with young mice (3.5 mo of age), as did renin mRNA levels. To determine whether aged CoRL responded less to RAAS blockade, enalapril and losartan were administered over 25 days following uninephrectomy in young and aged mice. The number of CoRL increased in young mice in response to enalapril and losartan. However, this was significantly lower in aged mice compared with young mice due to limited proliferation, but not recruitment. Gene expression analysis of laser-captured CoRL showed a substantial increase in mRNA levels for proapoptotic and prosenescence genes, and an increase in a major prosenescence protein on immunostaining. These results show that CoRL are lower in aged mice and do not respond to RAAS inhibition to the same extent as young mice.

Nocturia in older adults: implications for nursing practice and aging in place

Nocturia is a bothersome symptom that increases with age, resulting in sleep disruption, an increased risk of falls, and a greater likelihood of rating one's health as poor. It is often a symptom of conditions that cause low volume voiding, overproduction of urine across the day or only at night and a symptom of a sleep disorder. Nocturia affects quality of life and has an impact on aging in place, thus assessment and treatment are essential. Behavioral treatments should be explored first, keeping in mind what the affected older adult defines as the desired outcomes of treatment.

Excess diuresis and natriuresis during acute sleep deprivation in healthy adults

The transition from wakefulness to sleep is associated with a pronounced decline in diuresis, a necessary physiological process that allows uninterrupted sleep. The aim of this study was to assess the effect of acute sleep deprivation (SD) on urine output and renal water, sodium, and solute handling in healthy young volunteers. Twenty young adults (10 male) were recruited for two 24-h studies under standardized dietary conditions. During one of the two admissions, subjects were deprived of sleep. Urine output, electrolyte excretions, and osmolar excretions were calculated. Activated renin, angiotensin II, aldosterone, arginine vasopressin, and atrial natriuretic peptide were measured in plasma, whereas prostaglandin E2 and melatonin were measured in urine. SD markedly increased the diuresis and led to excess renal sodium excretion. The effect was more pronounced in men who shared significantly higher diuresis levels during SD compared with women. Renal water handling and arginine vasopressin levels remained unaltered during SD, but the circadian rhythm of the hormones of the renin-angiotensin-aldosterone system was significantly affected. Urinary melatonin and prostaglandin E2 excretion levels were comparable between SD and baseline night. Hemodynamic changes were characterized by the attenuation of nocturnal blood pressure dipping and an increase in creatinine clearance. Acute deprivation of sleep induces natriuresis and osmotic diuresis, leading to excess nocturnal urine production, especially in men. Hemodynamic changes during SD may, through renal and hormonal processes, be responsible for these observations. Sleep architecture disturbances should be considered in clinical settings with nocturnal polyuria such as enuresis in children and nocturia in adults.

Sleep deprivation impairs 12-hr urine volume excretion in old rats

Excessive nocturnal urine volumes (UVs) predict almost double the death rate in older adults. Furthermore, sleep-depriving environments may increase nocturnal UVs in old age. Thus, a pilot study was designed to examine the effects of sleep-depriving lighting treatments on the 12-hr UV excretion in young adult rats (6 months, n = 6), middle-aged rats (12 months, n = 12), old rats (16 months, n = 6), and old-old rats (>20 months, n = 5). Each animal was exposed continuously to the treatments beginning with 7 days each of standard laboratory lighting conditions of on 12 hr/off 12 hr, then 7 days continuous dim lighting, and finally 7 days of continuous dim lighting plus sleep deprivation with a noxious noise. Age group and lighting condition treatments influenced 24-hr urine volume excretion (F (2, 29) = 2.41, p = .007, r(2) = .8193). During sleep deprivation, rest-phase 12-hr urine volume excretion increased in both the old and old-old rats (F (2, 5) = 7.79, p < .00001).

Relative reference values for clinical chemical and haematological quantities in 'healthy' elderly people

A search of the literature revealed a paucity of data on reference values for clinical chemical and haematological quantities in reasonably 'healthy' ambulant persons above 65 years of age. On the basis of 90 papers, concerning 37 different types of quantities, the median values for men and for women at 30, 50, 65, and 80 years are calculated relative to the value in men at 30 years. This transformation reduces influences of analytical and demographic factors that have caused considerable systematic differences in the original data. The reference distribution is described as regards symmetry and the change in dispersion with age. The results are given in a table and show four types of changes with age: no significant variation, a fall, an increase or a maximum somewhere between 30 and 80 years; the type of change often depends on sex.

A lifetime of aldosterone excess: long-term consequences of altered regulation of aldosterone production for cardiovascular function

Up to 15% of patients with essential hypertension have inappropriate regulation of aldosterone; although only a minority have distinct adrenal tumors, recent evidence shows that mineralocorticoid receptor activation contributes to the age-related blood pressure rise and illustrates the importance of aldosterone in determining cardiovascular risk. Aldosterone also has a major role in progression and outcome of ischemic heart disease. These data highlight the need to understand better the regulation of aldosterone synthesis and its action. Aldosterone effects are mediated mainly through classical nuclear receptors that alter gene transcription. In classic epithelial target tissues, signaling mechanisms are relatively well defined. However, aldosterone has major effects in nonepithelial tissues that include increased synthesis of proinflammatory molecules and reactive oxygen species; it remains unclear how these effects are controlled and how receptor specificity is maintained. Variation in aldosterone production reflects interaction of genetic and environmental factors. Although the environmental factors are well understood, the genetic control of aldosterone synthesis is still the subject of debate. Aldosterone synthase (encoded by the CYP11B2 gene) controls conversion of deoxycorticosterone to aldosterone. Polymorphic variation in CYP11B2 is associated with increased risk of hypertension, but the molecular mechanism that accounts for this is not known. Altered 11beta-hydroxylase efficiency (conversion of deoxycortisol to cortisol) as a consequence of variation in the neighboring gene (CYP11B1) may be important in contributing to altered control of aldosterone synthesis, so that the risk of hypertension may reflect a digenic effect, a concept that is discussed further. There is evidence that a long-term increase in aldosterone production from early life is determined by an interaction of genetic and environmental factors, leading to the eventual phenotypes of aldosterone-associated hypertension and cardiovascular damage in middle age and beyond. The importance of aldosterone has generated interest in its therapeutic modulation. Disadvantages associated with spironolactone (altered libido, gynecomastia) have led to a search for alternative mineralocorticoid receptor antagonists. Of these, eplerenone has been shown to reduce cardiovascular risk after myocardial infarction. The benefits and disadvantages of this therapeutic approach are discussed.

Age-related changes in the renin-aldosterone system. Physiological effects and clinical implications

Age-related changes in the renin-aldosterone system in normal humans are well documented. The most pronounced changes are observed at the extremes of life: plasma renin activity and plasma aldosterone levels are highest in the newborn, and lowest in the elderly population. There is a close temporal and directional relationship between the age-related decrease in plasma renin activity and the age-related decrease in plasma aldosterone. The renin-aldosterone system is also influenced by sex and race. The activation of the renin-aldosterone system in newborns and infants probably represents an important physiological mechanism designed to maintain positive sodium balance. The decreases in plasma renin activity and plasma aldosterone levels observed in elderly persons are usually only modest, and are not associated with clinical alterations in fluid or electrolyte metabolism. The superimposition of a disease process, or the injudicious prescription of a drug, inhibiting renin release or angiotensin II production, could theoretically facilitate sodium wasting in newborns or infants, or precipitate hyporeninaemic hypoaldosteronism in older adults. The primary clinical importance of age-related changes in the renin-aldosterone system relates to its impact on the proper classification of an individual's renin-aldosterone profile when attempting to diagnose a clinical condition (e.g. low, normal or high renin hypertension). This is particularly true for newborns, infants and children to age 4, and for adults entering the sixth decade of life.

Alterations in the secretion of atrial natriuretic factor in atria from aged rats

We measured plasma atrial natriuretic factor levels and atrial natriuretic factor secretion by isolated left atria from aging rats to determine the secretory response to stretch and adrenergic stimulation. Systolic arterial pressure and right atrial pressure were measured in vivo. Twenty-four hours later, atria were removed and studied in vitro in a perifusion system. After removal, stabilization at 0.7 g tension, and equilibration for 65 minutes, atria were stretched by increasing external tension for 20 minutes. After reequilibration atria were perifused with phenylephrine, 10(-5) M, for an additional 30 minutes. Right atrial pressure was not different between young (3 months) and aged (16-24 months) rats. Aged rats had higher plasma atrial natriuretic factor levels (52 +/- 8 versus 21 +/- 6 pmol/l; p less than 0.05) than young rats. Basal atrial natriuretic factor secretory rate in vitro was greater in atria from aged rats than young rats (875 +/- 35 versus 402 +/- 22 pg/min; p less than 0.05). Atria from aged rats had an increased response to phenylephrine compared with young rats (1,687 +/- 143 versus 788 +/- 113 pg/min; p less than 0.05) when means were adjusted for basal secretory rate. The secretory response to stretch was less than that of young rats (673 +/- 37 versus 773 +/- 27 pg/min), although this difference was not significant (p = 0.07). Atrial natriuretic factor secretion in response to adrenergic stimulation is increased with aging, and these secretory responses may contribute to increased plasma levels that occur during aging. In contrast to increased adrenergic responses, atrial natriuretic factor secretion after external stretch is not increased in aging rats.

Association between sympathetic activity and the atherogenic serum cholesterol fraction

A possible modulating influence of noradrenergic activity on serum lipoproteins was assessed under placebo conditions and following 4 weeks of sympathetic neurone blockade with debrisoquine in 9 normal subjects, 11 patients with mild essential hypertension, 9 normotensive, and 9 hypertensive hemodialysis patients. Plasma norepinephrine (NE) did not differ significantly among groups on placebo and was consistently reduced (P less than 0.05-0.001) by sympathetic blockade. The latter also decreased (P less than 0.05-0.001) plasma total cholesterol (C) as well as low and very low density lipoprotein cholesterol (LDL + VLDL-C) in the three patient groups. In the two dialysis groups, basal levels of plasma triglycerides (Tg) were increased and high density lipoprotein cholesterol (HDL-C) was diminished (P less than 0.01-0.001); sympathetic blockade lowered Tg and raised HDL-C (P less than 0.01-0.001). In normal subjects, sympathetic blockade did not significantly modify plasma lipoproteins. In the three patient groups, significant correlations (r = 0.62 - 0.88; P less than 0.05 - less than 0.001) existed between (a) basal plasma NE and total C or LDL + VLDL-C and (b) debrisoquine-induced changes in NE and changes in total LDL + VLDL-C. These findings suggest that in essential hypertension as well as in hemodialysis patients, the atherogenic C fraction, represented by LDL + VLDL-C, may be modulated by the noradrenergic activity.

Plasma renin activity and albumin excretion in teenage type I diabetic subjects. A prospective study

Plasma renin activity (PRA) may be high among teenage and young adult insulin-dependent diabetic subjects. Supine PRA and stimulated PRA were therefore measured in 50 female and 50 male diabetic subjects, 13-20 years old, diagnosed before the age of 16. Fifty percent have been restudied after 4.6 +/- 0.2 (mean +/- SEM) years. Initially, 43% had high PRA (supine 4.0 +/- 0.37, stimulated 12.02 +/- 0.8 ng/ml/hr angiotensin I), 45% had normal activity (supine 2.89 +/- 0.26, stimulated 6.47 +/- 0.34 ng/ml/hr/angiotensin I), and 12% had low activity (supine 1.57 +/- 0.05, stimulated 3.09 +/- 0.08 ng/ml/hr/angiotensin I). Levels were directly associated with prepubertal duration of diabetes and were inversely associated with duration of diabetes after onset of puberty but not with total duration or patient age. Within 4.6 +/- 0.2 years the percentage of subjects with high PRA fell to 13%, and the percentage of those with low PRA rose to 35%. Initially 51% of the cohort had normal albumin excretion rates (AER) at rest and during exercise equal to or less than 10 micrograms/min/m2; 32% had elevated rates only during exercise of 39 +/- 5 micrograms/min/m2; 13% had elevated rates at rest of 41 +/- 8 micrograms/min/m2 and during exercise of 116 +/- 21 micrograms/min/m2; and 4% had clinical proteinuria at rest and during each exercise period equal to or greater than 150 micrograms/min/m2. After 5 years, 58% continued to have normal AER, or their AER improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.

Cardiovascular regulation and lipoprotein profile during administration of co-dergocrine in essential hypertension

Co-dergocrine has recently been demonstrated acutely to lower plasma norepinephrine (NE) and blood pressure (BP) in patients with essential hypertension, and similar results have been obtained during chronic administration of co-dergocrine to healthy men. The present study investigated the effect of 3 weeks of treatment with co-dergocrine 4 mg/day on BP, plasma catecholamines, certain other BP-regulating factors and serum lipoproteins in patients with essential hypertension. Compared to placebo conditions, co-dergocrine decreased supine BP and heart rate by -7% and the upright plasma NE level by -24%. Supine plasma NE also fell (-24%). Total cholesterol and the LDL + VLDL-cholesterol lipoprotein fraction were lowered by -6%. No significant change was observed in plasma renin activity, angiotensin II, aldosterone and epinephrine levels, whole blood and plasma volume, exchangeable sodium, and the cardiovascular responsiveness to NE, angiotensin II and isoproterenol. The findings suggest that in patients with essential hypertension, chronic treatment with co-dergocrine may slightly decrease sympathetic outflow and, at least in the short-term, lower the potentially atherogenic serum LDL + VLDL - cholesterol fraction.

Cardiovascular regulation during administration of co-dergocrine to normal subjects

Whether and to what extent activation of peripheral presynaptic dopamine2-receptors may modulate the release of norepinephrine (NE) and so affect blood pressure (BP) in normal or hypertensive man is not clear. The hydrogenated ergotoxine derivative, co-dergocrine, given in effective antihypertensive rather than excessive experimental doses, has recently been shown to act predominantly as a peripheral dopamine2-receptor agonist in several species. Accordingly, BP regulation assessed has been in 8 normal men on placebo and after 3 weeks on codergocrine 4 mg/day. Co-dergocrine significantly reduced urinary NE excretion from 43 to 33 micrograms/24 h, supine and upright plasma NE 21 to 16 and 49 to 36 ng/dl, respectively, heart rate (-8 and -5%, respectively) and upright systolic BP, 115 to 102 mm Hg; upright diastolic BP also tended to be lower. A standard pressor dose of infused NE was lowered from 131 to 102 ng/kg/min, and the relationship between NE-induced changes in BP and concomitant NE infusion rate or plasma NE concentration was displaced to the left. Exchangeable sodium and plasma volume tended to be slightly decreased. Plasma and urinary electrolytes and epinephrine, plasma renin activity and aldosterone levels, pressor responsiveness to angiotensin II, the chronotropic responses to isoproterenol, and the NE-induced rise in BP, plasma clearance of NE, glomerular filtration rate and effective renal plasma flow were not consistently modified. The findings are consistent with effective peripheral dopamine2-receptor agonism by co-dergocrine in humans. Peripheral presynaptic dopaminergic activation may modulate sympathetic activity and BP in normal man.

Norepinephrine-related mechanism in hypertension accompanying renal failure

Various blood pressure (BP)-regulating factors were assessed before and after 4 weeks of selective norepinephrine (NE) inhibition with the sympathetic neurone blocker, debrisoquine, in nine hypertensive, nine normotensive hemodialysis patients (HDP), and 11 normal subjects. On placebo, hypertensive HDP had an increased total blood volume (P less than 0.05) and exchangeable sodium (P less than 0.001), while both HDP groups had increased (P less than 0.05) plasma clearances of NE and angiotensin II (AII), and tended to have higher basal plasma NE, renin, and AII levels, and lower BP responses to NE or AII than normal subjects. Plasma epinephrine and the chronotropic dose of isoproterenol (CDI) did not differ significantly among groups. Debrisoquine lowered supine BP markedly in hypertensive HDP (on average from 181/107 to 148/88 mm Hg) and slightly in normotensive HDP (143/78 to 131/76 mm Hg), but not in normal subjects (116/74 to 120/79 mm Hg). In all groups, plasma NE, CDI, and NE pressor dose were reduced in parallel (by 35 to 75%; P less than 0.05 to less than 0.001), and the relation between stepwise increasing plasma NE and BP changes during NE infusion was commensurably displaced to the left (P less than 0.01). The remaining parameters were not changed consistently.

CONCLUSION

HDP, as normal subjects, respond to decreased sympathetic outflow with increased alpha- and beta-receptor sensitivity. Hypertension in HDP depends strongly on a NE-related mechanism. The latter seems to complement renin-angiotensin, sodium and fluid volume in the pathogenesis of high BP.

Pressor factors and responsiveness in hypertension accompanying diabetes mellitus

Hypertension accompanying diabetes mellitus may involve abnormalities in at least two major blood pressure-regulating systems: the body sodium-fluid volume state and cardiovascular reactivity. In metabolically stable nonazotemic diabetes, exchangeable sodium is increased by 10% on average, regardless of age, insulin dependence or nondependence, or the presence or absence of diabetic retinopathy or clinical nephropathy (proteinuria greater than or equal to 0.3 g/24 hr). Possible contributing mechanisms include renal sodium retention and an extravascular shift of fluid and sodium; intracellular accumulation is not excluded. Circulatory volume is normal or low and the total exchangeable sodium/blood volume ratio increased. In hypertensive diabetes, the latter abnormality is particularly pronounced; systolic pressure tended to correlate with exchangeable sodium (r = 0.47, p less than 0.001) and diastolic pressure with the plasma sodium/potassium ratio (r = 0.25, p less than 0.05). Plasma aldosterone, renin, epinephrine, and norepinephrine levels are generally normal or sometimes low in metabolically stable nonazotemic diabetic patients with normal or high blood pressure; the plasma clearance of norepinephrine also appears to be unaltered. The cardiovascular pressor responsiveness to norepinephrine is often exaggerated relative to concomitant plasma concentrations, regardless of age, type of antidiabetic treatment, or presence or absence of diabetic retinopathy, peripheral neuropathy, or high blood pressure. Pressor responsiveness to angiotensin II also may sometimes be increased relative to plasma renin levels. Sodium retention and diabetic vasculopathy of resistance vessels could be important complementary mechanisms of hyperreactivity. In diabetes with mild hypertension, diuretic treatment restored exchangeable sodium, norepinephrine pressor responsiveness, and blood pressure toward normal. Thus sodium retention and cardiovascular hyperreactivity tend to occur even at the normotensive, nonazotemic stage of diabetes and may concomitantly predispose for the frequent development of hypertension in the diabetic population.

Body sodium-blood volume state, aldosterone, and cardiovascular responsiveness after calcium entry blockade with nifedipine

Exchangeable sodium, blood volume, plasma norepinephrine (NE), epinephrine, renin and aldosterone levels, and pressor responses to infused NE or angiotensin II (AII) were assessed in ten patients with essential hypertension on placebo, following 6 to 8 weeks of calcium-antagonist nifedipine (NIF), 3 X 10 to 20 mg/day, and after 6 to 8 weeks on NIF combined with the diuretic chlorthalidone (CHLOR), 25 to 50 mg/day. Pressor effects of infused calcium also were evaluated on placebo and NIF. Supine blood pressure was decreased from 151/97 +/- 5/2 (SEM) to 132/88 +/- 6/2 mm Hg after NIF alone (P less than 0.05) and to 124/83 +/- 7/3 mm Hg after NIF + CHLOR (P less than 0.01). Body wt was increased from 72.7 to 73.9 kg on NIF alone (P less than 0.05), but decreased to 72.1 (P less than 0.05 compared with placebo) after adding CHLOR. Exchangeable sodium also rose from 2642 +/- 237 to 3360 +/- 266 mmoles on NIF (+ 27%; P less than 0.01) and returned to control values (2638 +/- 248 mmoles) after addition of CHLOR. Plasma volume was only slightly modified on NIF (from 2621 +/- 193 to 2751 +/- 160 ml; + 5%), but was reduced to 2232 +/- 231 ml on NIF + CHLOR (P less than 0.05). Responses of circulating aldosterone to AII were similarly diminished (P less than 0.01) during both conditions. Heart rate, supine and upright plasma renin, aldosterone and catecholamine levels, and pressor responses to NE, AII, or calcium were not consistently changed.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of piretanide on catecholamine metabolism, plasma renin activity and plasma aldosterone: a double-blind study versus furosemide in healthy volunteers

In a double-blind, crossover study, 8 male volunteers (mean age: 25.9 years) received successively 6 different regimens of two diuretics, piretanide and furosemide, with a 1-week wash-out period between each drug regimen. Piretanide (6 mg) or furosemide (40 mg) were given either once daily at 08.00 hours or twice daily at 08.00 and 12.00 hours or at 08.00 and 20.00 hours. Each of these phases lasted for 1 week. Serial measurements were performed on plasma renin activity, plasma aldosterone, plasma adrenaline, plasma noradrenaline, plasma dopamine, cumulative urinary excretion of aldosterone, urine volume and urine osmolality. Plasma catecholamines showed no clinically relevant changes during all three regimens of piretanide or furosemide dosage. Piretanide and furosemide both induced a short-term increase in plasma renin activity with a maximum about 4 hours after dosing which returned to initial levels after approximately 12 hours regardless of whether a single or twice daily dose had been given. After 1 week of piretanide given once daily, lower plasma renin activity was found than after furosemide. Furosemide given once daily caused higher plasma aldosterone concentrations than did piretanide. The lowest plasma aldosterone concentrations were found during the twice-daily piretanide regimen at 08.00 and 20.00 hours. Aldosterone excretion in urine was also higher during furosemide than during piretanide administration. Piretanide given twice daily at both 08.00 and 12.00 hours or 08.00 and 20.00 hours caused the most insignificant changes in aldosterone excretion. It is suggested that piretanide, in comparison to furosemide, activates the counter-regulatory mechanisms, which may diminish the antihypertensive effect of the diuretic, to a much lesser extent.

Increased serum high-density lipoprotein cholesterol in hypertensive men treated with the potent vasodilator carprazidil

The effects of the potent arteriolar vasodilator carprazidil on serum lipoproteins and various clinical, biochemical and endocrine parameters were assessed in 15 men with mild to moderate essential hypertension. Following a carprazidil monotherapy (average dose 50 to 60 mg/d) of 8 weeks (N = 15) or 16 weeks (N = 12) duration, blood pressure was decreased significantly (P less than 0.01), while serum high-density lipoprotein cholesterol (+ 26% and + 24%, respectively; P less than 0.01) and the alpha-lipoprotein fraction (+ 26% and + 41%) were increased. Low- and very low-density lipoprotein cholesterol, triglycerides, as well as mean body weight, blood and plasma volume, heart rate, and plasma renin, aldosterone, norepinephrine, and epinephrine were not consistently altered. These results indicate that treatment of hypertensive men with carprazidil in modest dosage may have a favorable influence both on blood pressure and serum lipoproteins.

Cardiovascular counterregulation during sympathetic inhibition in normal subjects and patients with mild hypertension

The influence of agents that inhibit sympathetic nerve activity on cardiovascular responsiveness as related to major pressor factors has been unclear. Therefore, these components were evaluated in 11 normal subjects and 13 patients with mild essential hypertension before and after 4 weeks of sympathetic neuron blockade with the agent debrisoquine. In these normal and mildly hypertensive subjects, sympathetic neuron blockade caused approximately similar decreases in urinary and supine or upright plasma norepinephrine (NE) levels (average changes in the two groups, -41% and -45%, respectively; p less than 0.05 to less than 0.005), the chronotropic dose of isoproterenol (-45% and -38%), and the NE pressor dose (-47% and -51%, p less than 0.01), while the relationship between NE-induced changes in blood pressure and concomitant plasma NE concentrations was displaced to the left (p less than 0.01). Supine heart rate was also lowered (-10% and -8%, p less than 0.05). Compared to the orthostatic variations during placebo conditions, mild postural decreases in blood pressure were apparent in both the normal and hypertensive groups (-8% and -7.5%). However, supine blood pressure was unchanged following debrisoquine treatment. Other parameters were also not consistently changed, such as total blood volume, exchangeable body sodium, urinary electrolytes, plasma epinephrine, renin, and angiotensin II (AII) levels, the pressor dose of infused AII, and the relationship between AII-induced changes in blood pressure and plasma AII measured before and during AII infusion. These findings demonstrate that the reduction in sympathetic outflow during sympathetic neuron blockade may elicit a hyperresponsiveness of alpha- and beta-adrenergic receptors that is equal in normal subjects and patients with mild essential hypertension.

Comparison of propranolol or hydrochlorothiazide alone for treatment of hypertension. III. Evaluation of the renin-angiotensin system

In this study, the relation between renin activity and therapeutic response to hydrochlorothiazide or propranolol was studied. Patients with a diastolic blood pressure of 95 to 114 mm Hg were treated with propranolol (40 to 320 mg twice daily) or hydrochlorothiazide (25 to 100 mg twice daily). The initial renin profiles were: low, 56 percent (n = 300); normal, 33 percent (n = 174); high, 11 percent (n = 60). A greater incidence of low and fewer high renin profiles (p less than 0.001) were observed in blacks. After furosemide administration (40 mg intravenously), 55 percent of patients (n = 291) had a low renin response and 45 percent (n = 240) had a normal renin response. No correlation between renin profile and renin response was observed, although low renin response and low renin profile occurred more frequently in older patients. Hydrochlorothiazide administration resulted in a greater decrement in diastolic blood pressure (p less than 0.05) in the total group. Irrespective of renin activity, both hydrochlorothiazide and propranolol reduced diastolic blood pressure. When renin profile was considered, no significant variation in response to hydrochlorothiazide therapy was observed, and there was a greater reduction in diastolic blood pressure in the patients with a high renin profile receiving propranolol. In comparing therapeutic response, patients with a low renin profile had a better response to hydrochlorothiazide, and propranolol was more effective in patients with a high renin profile. The anticipated effect of therapy on plasma renin activity was observed. Although these results are consistent with a volume-vasoconstrictor analysis of hypertension, the results of therapy could not have been prejudged from renin profile or responsivity. The slight differences observed do not warrant the expense of renin determinations when a simple determination of therapeutic response is sufficient.

Antihypertensive mechanism of diuretic treatment with chlorthalidone. Complementary roles of sympathetic axis and sodium

Twenty-three patients with untreated mild to moderate essential hypertension had on the average an abnormally increased cardiovascular pressor responsiveness to exogenous norepinephrine (NE), while plasma and urinary NE, exchangeable body sodium and blood volume were normal. An increased pressor responsiveness to angiotensin II in these patients was associated with a tendency for low plasma renin activity (PRA). Compared to placebo conditions, treatment with chlorthalidone, 100 mg/day, for 6 weeks significantly decreased blood pressure and exchangeable sodium in these hypertensive patients but not in ten normal subjects; blood volume and heart rate were unchanged in both groups. Chlorthalidone induced a marked increase in PRA, but only a mild increase in angiotensin II pressor dose. In contrast, the diuretic caused a greater increase in NE pressor dose than in plasma NE in the hypertensive group, thus improving the disturbed relationship between plasma NE and NE responsiveness in these patients. No significant modification of plasma NE and NE responsiveness occurred in diuretic-treated normal subjects. In addition to sodium and the renin-angiotensin system, the sympathetic regulatory axis seems to be involved in the antihypertensive mechanism of chlorthalidone. Thiazide-like diuretics may decrease blood pressure in essential hypertension in part by lowering an abnormally high cardiovascular NE responsiveness without causing an equivalent increase in circulating NE.

Correction of altered noradrenaline reactivity in essential hypertension by indapamide

Fourteen patients with untreated mild to moderate essential hypertension had, on average, an abnormally high cardiovascular reactivity to exogenous noradrenaline and angiotensin II, while plasma noradrenaline, renin activity, exchangeable body sodium, and blood volume were normal. Treatment with a low dose of indapamide (2.5 mg/day) for 6 weeks decreased blood pressure by 10% in these hypertensive patients but not in 13 normal control subjects. Plasma or blood volume and exchangeable sodium were not changed significantly; nevertheless, the latter, and body weight, tended to be decreased slightly. Though a mild reduction in extracellular sodium in both normal and hypertensive subjects appears possible, it may not fully explain per se the blood pressure-lowering effect of indapamide in essential hypertension. Indapamide induced a mild decrease in angiotensin II pressor responsiveness in normal or hypertensive subjects, but a possible depressor influence from this change was probably antagonized by a concomitant pronounced increase in plasma renin activity. In hypertensive patients, the abnormally high noradrenaline reactivity was corrected by indapamide without an accompanying increase in endogenous plasma noradrenaline levels. Indapamide-induced changes in blood pressure correlated with those in noradrenaline pressor dose. It was concluded, therefore, that indapamide may decrease blood pressure in essential hypertension at least in part by lowering an abnormally high cardiovascular noradrenaline reactivity without causing an equivalent increase in adrenergic nervous activity.

Pressor factors and cardiovascular pressor responsiveness in lean and overweight normal or hypertensive subjects

Several blood-pressure-regulating factors including exchangeable sodium, blood volume, plasma renin, aldosterone, norepinephrine (NE), and epinephrine (E) levels, urinary catecholamine excretion rates, and cardiovascular responsiveness to infused NE and angiotensin II (AII) were compared among age-matched subgroups of normal subjects (15 with normal weight, 15 with overweight) and patients with essential hypertension (15 with either normal weight, overweight, or obesity). Exchangeable sodium, blood volume, plasma and urinary sodium and potassium, plasma renin, aldosterone and epinephrine levels, and NE or E excretion rates did not differ significantly among the five subgroups. Minimal differences included a slightly higher heart rate in overweight patients than in overweight normal subjects (p less than 0.01) and a tendency for a higher plasma NE in overweight than in normal weight patients. Plasma NE obtained immediately before NE infusion as well as the plasma clearance of NE did not differ among the five subgroups except, however, for a somewhat low NE clearance in obese patients. The NE pressor dose tended to be lower in normal-weight hypertensive than in normal-weight normotensive subjects. No alteration was apparent in overweight or obese hypertensive patients. Pressor responses to AII were similar in the different subgroups. These findings suggest that overweight does not confer a unique aberration in the body sodium-volume state, circulating renin, aldosterone or catecholamines, or cardiovascular responses to NE or AII which result in hypertension.

Adrenergic mechanisms and blood pressure regulation in diabetes mellitus

Changes in blood pressure (BP) and plasma norepinephrine (NE) following various stimuli of the sympathetic, nervous system were studied in six healthy subjects and in 17 diabetic patients. The latter were subdivided in three groups: (1) six patients with neither peripheral neuropathy nor autonomic dysregulation, (2) six patients with severe peripheral neuropathy without autonomic dysregulation, and (3) five patients with autonomic dysregulation, three of whom suffered also from peripheral neuropathy. The following procedures were performed: (1) cold pressor test (2 min), (2) mechanical irritation of the skin by suction (0.75 kg/cm2, 10 min), (3) orthostasis (10 min), and (4) i.v. infusion of NE (50, 100, 200 ng kg-1 min-1 for 15 min each). Both the stimulated endogenous plasma NE levels and BP response to exogenous NE were the same in normal subjects, in diabetic controls and in diabetics with peripheral neuropathy without autonomic dysregulation. In contrast, diabetics with postural hypotension showed a less pronounced release of NE to standing (P less than 0.05), but not to cold pressor test and mechanical skin irritation. Furthermore, they showed increased vasoreactivity to the highest dose (P less than 0.05), but not to the lower doses of exogenous NE. Thus NE release and adrenergic BP regulation seem to be altered only in diabetics with clinical signs of autonomic dysregulation. These alterations can only be evaluated when patients are exposed to stimuli of higher intensity, such as orthostasis or infusion of a high NE dose.

Effects of tyramine on blood pressure and plasma catecholamines in normal and hypertensive subjects

Responses of blood pressure and plasma catecholamines to intravenous injection of tyramine at increasing dosage (30, 45, and 60 microgram/kg, respectively) were evaluated in 25 normal subjects and 20 patients with mild essential hypertension. Basal plasma norepinephrine and epinephrine concentrations before tyramine injections were similar in the two groups. Following tyramine injection, plasma epinephrine was unchanged. Responses of plasma catecholamines and blood pressure to tyramine were similar in the two groups. Plasma norepinephrine increased significantly 2 min after a dose of 30 microgram/kg, but higher tyramine doses failed to produce a further increase in plasma norepinephrine. In contrast, pressor responses to tyramine were dose-dependent. Maximal pressor responses were observed within 23 min after injection. These findings reveal a dissociation between changes in blood pressure and plasma norepinephrine following injection of tyramine. Lack of steady state may limit the value of tyramine bolus injections as a tool for the quantitation of pressor responsiveness to variations in endogenous sympathetic output. Alternatively, it is possible that the pressor effect of tyramine may be mediated at least in part by a norepinephrine independent mechanism.

Reversal of diuretic-induced increases in serum low-density-lipoprotein cholesterol by the betablocker pindolol

Seventeen patients with mild to moderate essential hypertension received during three consecutive 4 wk periods a matched placebo, the thiazide-like diuretic, clopamide in a low dosage of 5 mg/day, or this diuretic combined with the betablocker, pindolol in a low dosage of 10 mg/day. Compared to placebo conditions, clopamide monotherapy significantly increased serum low-density lipoprotein cholesterol (LDL-C) by 13% (p less than 0.025). Following addition of pindolol, serum LDL-C was restored to control values. These variations in serum LDL-C were unrelated to concomitant changes in blood pressure, plasma potassium, renin activity or aldosterone levels. Blood pressure in the supine position was reduced from 152/99 +/- 13/9 mm Hg (+ SD) to 141/93 +/- 15/7 mm Hg following diuretic-monotherapy and to 139/90 +/- 12/9 mm Hg following diuretic-betablocker combination treatment. These findings suggest that antihypertensive combination treatment with low doses of clopamide and pindolol is not only effective and well tolerated, but may also avoid the increase in serum LDL-C levels occurring when the thiazide-like diuretic is given alone.

Lasting improvement of renovascular hypertension by transluminal dilatation of atherosclerotic and nonatherosclerotic renal artery stenoses. A follow-up study

Sixteen consecutive patients with renovascular hypertension were treated by transluminal dilatation and observed during 6 - 39 months (mean 21.8 months). Poststenotic renal artery pressure increased (p less than 0.001) and the renal arteries were patent on angiograms taken immediately after dilatation. In 13 patients, angiography was repeated 2 - 9 months later; at that time the selective renal vein renin ratio had decreased (p less than 0.001). At the end of the follow-up, blood pressure was improved or normal in 14 cases. One of the eight patients with atherosclerosis was normotensive without treatment, compared with five of six patients with fibromuscular dysplasia (p less than 0.05). The results in two cases with vasculitis are uncertain. The four patients with relapses, one after intimal catheter dissection, were treated successfully by redilatation. Thus, renovascular hypertension can be improved by transluminal dilatation in patients with atherosclerosis and in patients with fibromuscular dysplasia with lasting success and a low morbidity rate.

Antihypertensive mechanism of the diuretic muzolimine in mild renal failure. Roles of sodium and cardiovascular norepinephrine responsiveness

Eighteen patients with mild impairment of renal function (glomerular filtration rate 65 +/- 5 ml/min:m +/- SEM) and hypertension (168/105 +/- 6/3 mmHg) were shown on average to have abnormally increased cardiovascular pressor responsiveness to infused norepinephrine (NE; p less than 0.05), whereas plasma and urinary NE, exchangeable body sodium and blood-volume did not differ significantly from normal. A slightly increased pressor responsiveness to angiotensin II was associated with a tendency to low plasma renin activity (PRA). Compared to placebo conditions, treatment with the loop-diuretic muzolimine in a mean dose of 35 +/- 2 mg/day for six weeks decreased blood-pressure and exchangeable sodium (p less than 0.05), and NE pressor responsiveness was restored to normal values, whilst plasma and urinary NE were not significantly changed. This was consistent with improvement of the initially abnormal relationship between NE levels and NE responsiveness factors. In contrast, the pressor dose of angiotensin II and PRA were increased to an approximatively similar extent during muzolimine treatment. These observations suggest that removal of body sodium and a decrease in NE reactivity without an equivalent increase in sympathetic nervous activity may be important complementary factors in the antihypertensive mechanisms of diuretic treatment in patients with mild renal functional impairment.

Comparative evaluation of the new vasodilator carprazidil and minoxidil in the treatment of moderate to severe hypertension

The efficacy and side effects of the new vasodilator carprazidil and the established vasodilator minoxidil were compared in 18 hypertensive patients inadequately controlled by 2 to 4 conventional drugs; the latter included diuretics, beta-blockers and/or sympatholytics and, in half the cases, vasodilators, such as hydralazine, diazoxide or the postsynaptic alpha-blocker prazosin. The vasodilators were withdrawn and, using a crossover design all patients received carprazidil (mean final dose 88 mg) and minoxidil (20 mg) for an average period of 5 to 6 months. The effects of the 2 agents appeared to be qualitatively and quantitatively similar. Both tended to cause sodium retention and an increase in heart rate, which required an increased dose of diuretic in one third of the cases or of a beta-blocker in a quarter. With this approach mean body weight and blood volume were not altered in the established phase of carprazidil or minoxidil treatment; heart rate and plasma norepinephrine tended to be only minimally increased, plasma renin was slightly increased, and plasma aldosterone and epinephrine were largely unchanged. Supine and upright blood pressure were reduced from initial values of 189/113 and 167/ 113 mm Hg, to 149/95 and 138/95 mm Hg (-18 and - 17%), respectively, during carprazidil, and to 154/95 and 141/96 mm Hg (-17 and - 15%) during minoxidil therapy. Hypertrichosis occurred with both agents in almost all patients, and limits their more prolonged use in females. No adverse side effects on haematological parameters, liver or renal function were observed, nor was antinuclear antibody detected. It is concluded that carprazidil and minoxidil are equivalent vasodilator agents in the treatment of severe hypertension, particularly in males.

Correction of altered noradrenaline reactivity in essential hypertension by indapamide

Fourteen patients with untreated mild to moderate essential hypertension had on average an abnormally high cardiovascular reactivity to exogenous noradrenaline and angiotension II, while plasma noradrenaline, renin activity, exchangeable body sodium, and blood volume were normal. Treatment with a low dose of indapamide (2.5 mg/day) for six weeks decreased blood pressure by 10% in these hypertensive patients but not in 13 normal control subjects. Plasma or blood volume and exchangeable sodium were not changed significantly; nevertheless, the latter, and body weight, tended to be decreased slightly. Though a mild reduction in extracellular sodium in both normal and hypertensive subjects appears possible, it may not per se fully explain indapamide's blood pressure-lowering effect in essential hypertension. Indapamide induced a mild decrease in angiotensin II pressor responsiveness in normal or hypertensive subjects, but a possible depressor influence from this change was probably antagonised by a concomitant pronounced increase in plasma renin activity. In hypertensive patients, the abnormally high noradrenaline reactivity was corrected by indapamide without an accompanying increase in endogenous plasma noradrenaline levels. Indapamide-induced changes in blood pressure correlated with those in noradrenaline pressor dose. It was concluded, therefore, that indapamide may decrease blood pressure in essential hypertension at least in part by lowering an abnormally high cardiovascular noradrenaline reactivity without causing an equivalent increase in adrenergic nervous activity.

Acute hypercalcemic hypertension in man: role of hemodynamics, catecholamines, and renin

The effect of acute hypercalcemia on blood pressure, blood volume, hemodynamic parameters, plasma norepinephrine, epinephrine, dopamine, renin, and aldosterone concentrations was investigated. After 1 hour of equilibration, 10 patients received an infusion of calcium gluconate in 5% dextrose (calcium 15 mg/kg of body wt in 3 hours). The calcium infusion increased the mean serum calcium from 8.7 to 13.0 mg/dl, the systolic blood pressure from 144 +/- 10 to 184 +/- (SEM) 12 mm Hg (P less than 0.001), the diastolic pressure from 78 +/- 4 to 93 +/- 5 mm Hg (P less than 0.01). The plasma volume was decreased by 9% (P less than 0.001), whereas the hematocrit was increased (P less than 0.05). Heart rate and cardiac output remained unchanged. Total peripheral resistance was increased from 1643 +/- 223 to 2256 +/- 387 dyne.sec/cm5 (P less than 0.05). The plasma epinephrine concentration rose from 4.5 +/- 0.7 to 6.9 +/- 1.2 ng/dl (P less than 0.01). The plasma norepinephrine concentration was unchanged after 2 hours and increased only slightly after 3 hours of calcium infusion. Plasma renin, aldosterone, and dopamine concentrations were not significantly changed. These findings demonstrate that acute hypercalcemic hypertension is mediated by an increase in peripheral vascular resistance. Hypercalcemic hypertension may be induced by a direct effect of calcium on blood vessels; calcium-mediated increase in adrenal epinephrine release may play a mild contributory role, and plasma volume contraction, an inhibitory role.

Plasma aldosterone response to angiotensin II in sodium-restricted elderly subjects with essential hypertension

The plasma aldosterone (PA) response to sodium restriction (25 mEq daily for 4 days) and to graded infusions of angiotensin II (AII, 2, 4 and 8 ng/kg/min each for 30 min) during a low-sodium intake were studied in 15 elderly subjects with mild essential hypertension versus 10 elderly normotensive subjects. The PA response to sodium restriction relative to changes in plasma renin activity (PRA) was estimated by the ratio of PA increment to PRA increment after sodium restriction (delta PA/delta PRA). THe PA response to graded AII infusions was determined by the increment of PA above the basal level after each dose of AII. In 10 of the 15 elderly hypertensive subjects whose PRAs responded normally to sodium restriction, the delta PA/delta PRA ratios and PA increments during the graded AII infusions were similar to those in the elderly normotensive subjects. However, in the remaining 5 elderly hypertensive subjects whose PRAs responded subnormally to sodium restriction, the delta PA/delta PRA ratios were high and the PA increments greater during the graded AII infusions. THe increments of mean blood pressure during the graded AII infusions were similar in the foregoing 10 of 15 hypertensive subjects, and significantly greater during the AII infusion rates of 4 and 8 ng/kg/min in the remaining 5 hypertensive subjects when compared with those in the normotensive subjects. Apparently some subjects with essential hypertension, whose PRAs response subnormally to sodium restriction, have an abnormally enhanced adrenal responsiveness to AII under the conditions of low-sodium intake.

Pressor factors and cardiovascular pressor responsiveness in borderline hypertension

The role of various pressor factors and cardiovascular responsiveness to norepinephrine or angiotensin II in the pathogenesis of borderline hypertension was evaluated. Exchangeable body sodium, blood volume, plasma renin activity, norepinephrine or dopamine levels, and norepinephrine or epinephrine excretion rates were similar between 24 patients with borderline hypertension (mean age 34 +/- 4 (SEM) years and 22 normal subjects matched for age; the patients had a slight increase in supine plasma epinephrine. Pressor doses of norepinephrine or angiotensin II were significantly lower (p less than 0.01 and 0.001, respectively) in the borderline hypertensive group. These findings suggest that borderline hypertension may be maintained by inappropriately increased cardiovascular response to norepinephrine and angiotensin II in the presence of normal sympathetic and renin activity and a normal body sodium-volume state.

Age-rated profile of cardiovascular reactivity to norepinephrine and angiotensin II in normal and hypertensive man

The interrelationships among age, cardiovascular pressor reactivity to intravenously infused norepinephrine (NE) or angiotensin II, and endogenous plasma NE or renin (PRA) levels were evaluated i 31 normal subjects and 37 patients with essential hypertension. In normal subjects both angiotensin II pressor dose and PRA decreased progressively with aging. Angiotensin pressor dose correlated positively with PRA (r = 0.41, P < 0.025) and inversely with age (r = -0.46, P < 0.02). NE pressor dose and basal plasma NE were also positively correlated (r = 0.53, P < 0.005), but the two factors remained largely unchanged with aging. Findings in essential hypertension differed in certain aspects. Angiotensin II pressor dose did not correlate with either basal PRA or age; and pressor doses of NE and angiotensin II tended to be lower in some patients than in normal subjects. These findings indicate that aging is accompanied by a physiologic increase in cardiovascular reactivity to angiotensin II, probably due to a concomitant decrease in circulating renin. The dissociation between angiotensin pressor dose and PRA in essential hypertension suggests an interference from an other factor.

Serum cortisol response to acute myocardial infarction in the aged

The adrenocortical response to acute myocardial infarction in aged patients was studied by measuring serum cortisol concentration (radioimmunoassay) at the time of hospital admission. The mean serum cortisol level in 9 patients over 80 years old was similar to that in 5 patients less than 60 years old. In all patients who died, or in whom shock developed, the serum cortisol concentration was significantly elevated.

Recent pathogenic aspects in essential hypertension and hypertension associated with diabetes mellitus

The sympathetic system, the body sodium-fluid volume state, the renin-angiotensin system, functional and structural characteristics of the heart and blood vessels, and some other components are important complementary factors in blood pressure regulation. A deviation from the normal equilibrium among these components, with a persisting non-physiologic increase in pressor factor(s) or in the basal vascular tone and/or cardiovascular reactivity to pressor factors, leads to hypertension. This review discusses recent observations and concepts regarding the pathogenesis of essential hypertension and hypertension associated with diabetes mellitus. It focuses on the roles of various pressor factors as well as cardiovascular pressor responsiveness in the genesis of high blood pressure and in the antihypertensive mechanism of diuretic treatment.

Essential hypertension: relationship between renin and blood pressure

Supine (basal) plasma renin activity (PRA) and mean arterial pressure (MAP) were determined in 564 essential hypertensives grouped by age and sex. Mean supine PRA showed an age-dependent significant decrease (p < 0.001), whereas an increase in MAP was observed with age (p < 0.001). There were no sex-related differences both in PRA and MAP. In younger hypertensives (15-34 years) of both sexes an inverse correlation was obtained between PRA and MAP, whereas middle-aged men (35-50 years) and male and female hypertensives of older age (> 51 years) showed a positive relationship between these two parameters. No significant correlation was seen between PRA and MAP in middle aged women (35-50 years). The observed findings suggest a negative feed-back mechanism between blood pressure and renin release in younger hypertensives. In older patients this mechanism is disturbed probably through hypertension induced changes in the renovascular system resulting in an inappropriate large release of renin for a given level of blood pressure. This conversion from an inverse to a positive relationship between PRA and MAP occurred earlier in male than in female patients. Finally, our results support the assumption that in essential hypertension changes in renin secretion are rather the sequel than the cause of elevated blood pressure.