Hyperparathyroidism, platelet intracellular free calcium and hypertension in chronic renal failure

Role of hypertension in progression of pediatric CKD

Hypertension is frequent in children with chronic kidney disease (CKD). Its prevalence varies according to CKD stage and cause. It is relatively uncommon in children with congenital kidney disease, while acquired kidney disease is associated with a higher prevalence of hypertension. Studies in children with CKD utilizing ambulatory blood pressure monitoring also showed a high prevalence of masked hypertension. Uncontrolled and longstanding hypertension in children is associated with progression of CKD. Aggressive treatment of high blood pressure should be an essential part of care to delay CKD progression in children.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Vascular Calcification Mechanisms: Updates and Renewed Insight into Signaling Pathways Involved in High Phosphate-Mediated Vascular Smooth Muscle Cell Calcification

Vascular calcification (VC) is associated with aging, cardiovascular and renal diseases and results in poor morbidity and increased mortality. VC occurs in patients with chronic kidney disease (CKD), a condition that is associated with high serum phosphate (Pi) and severe cardiovascular consequences. High serum Pi level is related to some pathologies which affect the behaviour of vascular cells, including platelets, endothelial cells (ECs) and smooth muscle cells (SMCs), and plays a central role in promoting VC. VC is a complex, active and cell-mediated process involving the transdifferentiation of vascular SMCs to a bone-like phenotype, systemic inflammation, decreased anti-calcific events (loss of calcification inhibitors), loss in SMC lineage markers and enhanced pro-calcific microRNAs (miRs), an increased intracellular calcium level, apoptosis, aberrant DNA damage response (DDR) and senescence of vascular SMCs. This review gives a brief overview of the current knowledge of VC mechanisms with a particular focus on Pi-induced changes in the vascular wall important in promoting calcification. In addition to reviewing the main findings, this review also sheds light on directions for future research in this area and discusses emerging pathways such as Pi-regulated intracellular calcium signaling, epigenetics, oxidative DNA damage and senescence-mediated mechanisms that may play critical, yet to be explored, regulatory and druggable roles in limiting VC.

Österreichischer Blutdruckkonsens 2019

Erhöhter Blutdruck bleibt eine Hauptursache von kardiovaskulären Erkrankungen, Behinderung und frühzeitiger Sterblichkeit in Österreich, wobei die Raten an Diagnose, Behandlung und Kontrolle auch in rezenten Studien suboptimal sind. Das Management von Bluthochdruck ist eine häufige Herausforderung für Ärztinnen und Ärzte vieler Fachrichtungen. In einem Versuch, diagnostische und therapeutische Strategien zu standardisieren und letztendlich die Rate an gut kontrollierten Hypertoniker/innen zu erhöhen und dadurch kardiovaskuläre Erkrankungen zu verhindern, haben 13 österreichische medizinische Fachgesellschaften die vorhandene Evidenz zur Prävention, Diagnose, Abklärung, Therapie und Konsequenzen erhöhten Blutdrucks gesichtet. Das hier vorgestellte Ergebnis ist der erste Österreichische Blutdruckkonsens. Die Autoren und die beteiligten Fachgesellschaften sind davon überzeugt, daß es einer gemeinsamen nationalen Anstrengung bedarf, die Blutdruck-assoziierte Morbidität und Mortalität in unserem Land zu verringern.

Towards cardiovascular risks in children with chronic kidney disease: a prospective cohort study

Background: Children with chronic kidney disease (CKD) are at substantially high risk of morbidity and mortality from cardiovascular disease (CVD). Although this issue has been extensively studied in adults, little is known whether similar associations exist in the paediatric population. We therefore aimed to evaluate the cardiac structure and function in children with CKD, and investigate the factors that contribute to the development of CVD. Methods: A prospective cohort was established following 40 children with CKD treated in the nephrology unit at a high-volume, tertiary, teaching hospital and compared to age- and gender-matched controls of the same number.  We reviewed the patients’ medical records, assessed growth parameters, measured blood pressure, took blood samples, and performed echocardiography. Results: More than half of the CKD patients are hypertensive (N = 22; 55%) and were found to have a higher proportion of increased left ventricular mass index (LVMI) (75.5%; P = 0.001). In contrast, we did not find any significant association between CKD and both valvular calcification & left ventricular (LV) fractional shortening (FS) in children (P = 0.314). Furthermore, high LVMI is found to be correlated well with the following: anaemia, hypertension, CKD duration > one year, hyperparathyroidism, estimated glomerular filtration rate (eGFR) < 15ml/minute/1.73 m2 and death (P < 0.05). Conclusions: Despite the fact that LV systolic function is preserved and valvular calcification is usually absent, left ventricular hypertrophy (LVH) is common in children with CKD. Hypertension, anaemia, hyperparathyroidism, as well as the severity and duration of renal impairment, are amongst the additional risk factors that predispose to LVH. We contribute this study to the growing information of the review articles regarding the association between CKD and CVD in paediatrics.

Hypertension in patients on dialysis: diagnosis, mechanisms, and management

Hypertension (blood pressure > 140/90 mm Hg) is very common in patients undergoing regular dialysis, with a prevalence of 70-80%, and only the minority has adequate blood pressure (BP) control. In contrast to the unclear association of predialytic BP recordings with cardiovascular mortality, prospective studies showed that interdialytic BP, recorded as home BP or by ambulatory blood pressure monitoring in hemodialysis patients, associates more closely with mortality and cardiovascular events. Although BP is measured frequently in the dialysis treatment environment, aspects related to the measurement technique traditionally employed may be unsatisfactory. Several other tools are now available and being used in clinical trials and in clinical practice to evaluate and treat elevated BP in chronic kidney disease (CKD) patients. While we wait for the ongoing review of the CKD Blood Pressure KIDGO guidelines, there is no guideline for the dialysis population addressing this important issue. Thus, the objective of this review is to provide a critical analysis of the information available on the epidemiology, pathogenic mechanisms, and the main pillars involved in the management of blood pressure in stage 5-D CKD, based on current knowledge.

Plasma microRNA-155-5p is increased among patients with chronic kidney disease and nocturnal hypertension

MicroRNAs play multiple roles in the regulation of blood pressure (BP). Nevertheless, to date, no study has assessed the association between microRNA plasma expression and BP control in chronic kidney disease (CKD) patients. Given this background, we evaluated the plasma expression of miR-155-5p, a translational inhibitor of angiotensin receptor type I, in CKD patients, to determine the association between miR-155-5p level and BP control. In this single-center cross-sectional study, we analyzed the miR-155-5p concentration by quantitative reverse transcriptase polymerase chain reaction using the U6 snRNA as a reference gene and 24-hour ambulatory blood pressure monitoring in CKD patients (stage ≥2) in relation to a control group of healthy age-matched and gender-matched individuals, with normal BP proven by the ambulatory blood pressure monitoring. We enrolled a total of 105 patients with CKD (stages 2-5, including 33 kidney renal transplant recipients), aged 59 ± 14 years; 47% males and 26 healthy volunteers (aged 55 ± 13, 50% male). Within the study group, a total of 36 patients (40%) presented with an average 24-hour systolic BP (SBP) ≥130 mm Hg and 41 patients (45%) presented nocturnal hypertension (NHT; SBP ≥120 mm Hg or diastolic BP ≥ 70 mm Hg). miRNA-155-5p was increased in plasma of CKD patients with median expression relative to control subjects equal to 2.92 (1.34-5.58). Interestingly, the plasma miRNA-155-5p expression was significantly higher in patients with NHT: 4.04 (2.92-10.8) versus 2.01 (1.21-3.07), P = .001 and its expression maintained an independent association with the average nocturnal SBP (coefficient B = 4.368, P = .047) by a multivariate regression analysis adjusted for confounders. The miR-155-5p was increased among CKD patients and further increased among subjects presenting with NHT. Further studies are warranted to determine the role of this non-coding RNA as a potential novel biomarker and therapeutic target in the non-dipping CKD individuals, characterized by increased cardiovascular risk.

Hypertension and hemodialysis: pathophysiology and outcomes in adult and pediatric populations

Hypertension is prevalent in adult and pediatric end-stage renal disease patients on hemodialysis. Volume overload is a primary factor contributing to hypertension, and attaining true dry weight remains a priority for nephrologists. Other contributing factors to hypertension include activation of the sympathetic and renin-angiotensin-aldosterone systems, endothelial cell dysfunction, arterial stiffness, exposure to hypertensinogenic drugs, and electrolyte imbalances during hemodialysis. Epidemiologic studies in adults show that uncontrolled hypertension results in cardiovascular morbidity, but reveal increased mortality risk at low blood pressure, so that it remains unclear what the target blood pressure should be. Despite the lack of a definitive BP target, gradual dry weight reduction should be the first intervention for BP control. Renin-angiotensin-aldosterone system inhibitors have been shown to improve cardiovascular morbidity and mortality and are recommended as the initial pharmacologic therapy for hypertensive hemodialysis patients. Short-daily or nocturnal hemodialysis are also good therapeutic options for these patients. It is already established that hypertension in pediatric hemodialysis patients is associated with adverse cardiovascular outcomes, and there is emerging evidence that the mechanisms causing hypertension are similar to adults. Hypertension in adult and pediatric hemodialysis patients warrants aggressive management, although clinical trial evidence of a target BP that improves mortality does not currently exist.

Epidemiology of interdialytic ambulatory hypertension and the role of volume excess

BACKGROUND

The epidemiology of hypertension among hemodialysis (HD) patients is difficult to describe accurately because of difficulties in the assessment of blood pressure (BP).

METHODS

Using 44-hour interdialytic ambulatory BP measurements, we describe the epidemiology of hypertension in a cohort of 369 patients. To seek correlates of hypertension control, antihypertensive agents were withdrawn among patients with controlled hypertension and ambulatory BP monitoring was repeated.

RESULTS

Hypertension (defined as an average ambulatory systolic BP ≥135 mm Hg or diastolic BP ≥85 mm Hg, or the use of antihypertensive medications) was prevalent in 82% of the patients and independently associated with epoetin use, lower body mass index and fewer years on dialysis. Although 89% of the patients were being treated, hypertension was controlled adequately in only 38%. Poor control was independently associated with greater antihypertensive drug use. Inferior vena cava (IVC) diameter in expiration was associated with increased risk of poorly controlled hypertension both in cross-sectional analysis and after withdrawal of antihypertensive drugs.

CONCLUSIONS

Interdialytic hypertension is highly prevalent and difficult to control among HD patients. End-expiration IVC diameter is associated with poor control of hypertension in cross-sectional analyses as well as after washout of antihypertensive drugs. Among HD patients, an attractive target for improving hypertension control appears to be the reduction of extracellular fluid volume.

Aortic arch calcification and clinical outcome in patients with end-stage renal disease

Vascular calcification is very common in end-stage renal disease, especially in hemodialysis patients. Vascular calcification is associated with poor prognosis in hemodialysis patients. The transformation of vascular smooth muscle cells into osteoblast-like cells seems to be a key element in the pathogenesis of vascular calcification. In addition to traditional risk factors including hypertension and dyslipidemia, hemodialysis patients possess a number of non-traditional cardiovascular risk factors, which may be associated with the pathogenesis of vascular calcification, such as duration of dialysis and imbalance of mineral metabolism. The severity of vascular calcification can be assessed with computed tomography (CT), but a simple technique is required as a routine practice. In an attempt to evaluate the extent of vascular calcification, we have proposed a simple non-invasive technique for estimating aortic arch calcification (AoAC) in hemodialysis patients. The present review summarizes the following aspects: (i) a method of estimating AoAC and the correlation between AoAC score estimated by chest X-ray and AoAC volume evaluated by multi-detector CT as a gold standard, (ii) relation of the presence of AoAC to the prevalence of cardiovascular diseases, and (iii) Kaplan-Meier analysis in terms of cardiovascular mortality in patients with AoAC compared to those without AoAC. We suggest that screening patients undergoing dialysis for the presence of AoAC is a cost-effective, efficient way to identify those patients at the highest risk of cardiovascular events and will allow for the treatment strategies to prevent vascular calcification.

Hypertension in small animal kidney disease

Kidney disease is commonly associated with hypertension in dogs, cats and other species. There are multiple mechanisms underlying the development of renal hypertension including sodium retention, activation of the renin-angiotensin system and sympathetic nerve stimulation. The relative importance of these and other mechanisms may vary both between species and according to the type of kidney disease that is present. Consideration of underlying disease mechanisms may aid in the rational choice of therapy in hypertensive patients.

Management of hypertension in hemodialysis patients

Hypertension is very common in patients with chronic kidney disease and is present in most patients with end-stage renal disease (ESRD). Hypertension is largely responsible for premature cardiovascular disease in dialysis patients. The pathophysiology of hypertension in ESRD is complex, and multiple mechanisms are likely involved in blood pressure dysregulation in patients on hemodialysis. Some of these patients demonstrate resistant hypertension. Aggressive control of hypertension in ESRD/dialysis is mandatory. Generally, nonpharmacologic treatments are not enough to achieve the goal blood pressure levels in dialysis patients. Multiple antihypertensive drugs are often necessary. Drugs that block the renin-angiotensin system offer a number of advantages for patients with chronic kidney disease or ESRD, but additional drug classes are often needed to achieve effective blood pressure control in dialysis patients. Physicians treating hypertension in dialysis patients should be familiar with the pharmacokinetic properties of antihypertensive drugs in renal failure and choose the dosages accordingly. Vigorous control of hypertension is recommended to reduce the disease burden in patients with ESRD.

Relation of oral 1alpha-hydroxy vitamin D3 to the progression of aortic arch calcification in hemodialysis patients

The role of decreased active vitamin D levels on vascular calcification has not been elucidated in hemodialysis (HD) patients. The aim of the present study was to evaluate the relationship between progression of aortic arch calcification (AoAC) and prescribed dose of 1alpha-hydroxy vitamin D. The enrolled study subjects were 65 (40 men and 25 women) HD patients. Calcification of the aortic arch was semiquantitatively estimated with a score (AoACS) on plain chest radiology. Change in AoACS (DeltaAoACS) was obtained by subtracting the baseline AoACS value from the follow-up AoACS value. The second assessment was performed from 2 years after the first determination. The nonprogressors (63.2 +/- 14.5 years) were significantly younger than the progressors (68.2 +/- 10.8 years) (P = 0.0419). In addition, prescribed dose of 1alpha-hydroxy vitamin D3 was significantly higher in the nonprogressors (125.5 +/- 109.1 microg) than progressors (84.8 +/- 81.1 microg) (P = 0.0371). Multiple regression analysis revealed prescribed dose of 1alpha-hydroxy vitamin D(3) (beta value = -0.324, P = 0.0051) as well as DBP (beta value = -0.418, P = 0.007), serum levels of P (beta value = 0.333, P = 0.006) and C-reactive protein (beta value = 0.237, P = 0.0048) to be significant independent determinants of DeltaAoACS. In conclusion, the evaluation of AoACS on chest radiography is a very simple tool in HD patients. Active vitamin D therapy seems to protect patients from developing vascular calcification.

Acute cardiovascular effects of the calcimimetic R-568 and its enantiomer S-568 in rats

Calcimimetics increase the sensitivity of the calcium sensing receptor (CaSR) to calcium ions (Ca(2+)) and allow for efficient control of uraemic hyperparathyroidism. Recent studies suggested an additional blood pressure-lowering action, the underlying mechanisms are as yet unknown. We infused R-568 and its enantiomer S-568, which has little activity at the CaSR, in anaesthetized rats. Mean arterial blood pressure (MAP) and heart rate (HR) were measured in the femoral artery; renal blood flow (RBF) and mesenteric blood flow (MBF) were measured locally. Infusion of R-568 at 0.7 mg/kg per 10 min into the femoral vein, a dose known to reduce levels of parathyroid hormone (PTH) and Ca(2+) in plasma, did not affect blood pressure or heart rate. Infusion of 2.1 mg/kg per 3 min of R-568 and S-568 into the femoral vein significantly reduced MAP by 26 +/- 4.5 and 23.7 +/- 3.1% and HR by 7.8 +/- 2.9 and 5.8 +/- 2.0%, respectively. Intra-arterial infusions of R-568 increased blood flow in a dose-dependent fashion. At plasma concentrations of 70 micromol/l R-568 and S-568 increased RBF by 17 +/- 3 and 15 +/- 3% and MBF by 28 +/- 5 and 29 +/- 5%. The effects on blood flow were greater in the mesenteric artery than in the renal artery, but not different between both compounds.The calcimimetic R-568 exerts acute, CaSR-independent, hypotensive effects via vasodilation and negative chronotropy at concentrations exceeding those required for modulation of PTH secretion.

Pharmacological control of secondary hyperparathyroidism in chronic hemodialysis patients: cinacalcet is coming to Japan

Secondary hyperparathyroidism has a significant impact on morbidity and mortality due to skeletal and extraskeletal manifestations. Cinacalcet, a newly developed calcimimetic, is reported to decrease parathyroidism, as well as serum levels of phosphorus (P) and calcium (Ca) and therefore Ca x P product. Available evidence has shown that cinacalcet decreases the rate of parathyroidectomy and bone fracture in hemodialysis patients, but the death rate remains the same. Although, it is not yet available in Japan, cinacalcet is expected to be available as a possible drug for patients undergoing hemodialysis due to secondary hyperparathyroidism associated with refractory hyperphosphatemia and hypercalcemia. Except for the high cost, cinacalcet will be a welcome therapeutic option for end-stage renal disease and probably also for pre-end-stage renal disease patients. Dietary phosphate restriction and adequate hemodialysis, however, are still the main strategy for the control of hyperphosphatemia and secondary hyperparathyroidism.

Hypertension in children with chronic kidney disease: pathophysiology and management

Arterial hypertension is very common in children with all stages of chronic kidney disease (CKD). While fluid overload and activation of the renin-angiotensin system have long been recognized as crucial pathophysiological pathways, sympathetic hyperactivation, endothelial dysfunction and chronic hyperparathyroidism have more recently been identified as important factors contributing to CKD-associated hypertension. Moreover, several drugs commonly administered in CKD, such as erythropoietin, glucocorticoids and cyclosporine A, independently raise blood pressure in a dose-dependent fashion. Because of the deleterious consequences of hypertension on the progression of renal disease and cardiovascular outcomes, an active screening approach should be adapted in patients with all stages of CKD. Before one starts antihypertensive treatment, non-pharmacological options should be explored. In hemodialysis patients a low salt diet, low dialysate sodium and stricter dialysis towards dry weight can often achieve adequate blood pressure control. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers are first-line therapy for patients with proteinuria, due to their additional anti-proteinuric properties. Diuretics are a useful alternative for non-proteinuric patients or as an add-on to renin-angiotensin system blockade. Multiple drug therapy is often needed to maintain blood pressure below the 90th percentile target, but adequate blood pressure control is essential for better renal and cardiovascular long-term outcomes.

Associations between sympathetic activity, plasma concentrations of renin, aldosterone, and parathyroid hormone, and the degree of intractability of blood pressure control in modialysis patients

This study was designed to examine how such factors as hemodialysis parameters, body mass index, renin and aldosterone concentrations, sympathetic nervous activity, and parathyroid hormone concentrations are associated with the control of hypertension in hemodialysis patients. Hemodialysis patients (n=114) were grouped into four categories. Group 1 had normal BP without antihypertensive medication. Group 2 needed one antihypertensive drug, Group 3 needed combination of two or three categories of antihypertensive drugs without minoxidil. Group 4 needed more than three categories of antihypertensive drugs including minoxidil. Parathyroid hormone, beta2-microglobulin, renin and aldosterone, epinephrine, norepinephrine, and hemodialysis parameters were measured. The fractional clearance of urea as Kt/V urea was significantly lower in Group 3 and Group 4 than in Group 2 (p<0.01). Concentrations of parathyroid hormone were significantly higher in Group 4 than the other groups (p<0.01). Pre-hemodialysis norepinephrine concentrations were significantly higher in Group 4 than the other groups (p<0.05). Traditional factors associated with hypertension did not seem to be relevant to the degree of hypertension in hemodialysis patients in the present study. In conclusion, poor Kt/V urea, elevated parathyroid hormone concentrations, and elevated concentrations of plasma norepinephrine seemed to be the factors that might be associated with control of hypertension in hemodialysis patients.

Diastolic dysfunction and abnormality of the Na+/Ca2+ exchanger in single uremic cardiac myocytes

Cardiovascular disease is the most common cause of death in patients with end-stage renal disease, possibly due to a specific "uremic cardiomyopathy". This study investigated the function of the Na(+)/Ca(2+) exchanger in single cardiac myocytes from a model of early renal impairment. Mild uremia was induced by partial (5/6) nephrectomy in male Wistar rats. After 4 weeks, ventricular myocytes were isolated, loaded with the fluorescent Ca(2+) indicator indo-1, and contractile function and calcium transients recorded following electrical pacing at 0.2 Hz. Relaxation from rapid cooling contractures (RCCs) was also studied. Cells from uremic animals (U) were hypertrophied compared with controls (C), with a significant increase in width (14%; P<0.02) and cross-sectional area (13%; P<0.03). There was a significant increase in diastolic intracellular Ca(2+) ratio in the uremic cells (C, 0.33+/-0.00 vs U, 0.37+/-0.02; P<0.02), although the amount of calcium released per twitch was similar. Uremic cells were slower to relax following RCCs, however when Na(+)/Ca(2+) exchange was inhibited using a Na(+)-free/Ca(2+)-free solution, this difference was abolished. Under these conditions, there was little difference in the relaxation rate of control cells, indicating that the Na(+)/Ca(2+) exchanger plays only a minor role in relaxation in normal rat myocytes. However in uremia, the data indicate that the Na(+)/Ca(2+) exchanger actively interfered with relaxation, possibly by working in reverse rather than forward mode. These results indicate that myocyte relaxation and Ca(2+) handling are abnormal in early uremia and may provide further evidence for the existence of a specific "uremic cardiomyopathy".

Etiology and management of hypertension in chronic kidney disease

The kidneys are vital in the pathogenesis of hypertension and are also pathologically affected by the presence of hypertension. The prevalence of hypertension in chronic kidney disease (CKD) depends on age, the severity of renal failure, and proteinuria. The intricate and inextricable relationship between CKD and hypertension seems to cause cardiovascular disease that has assumed epidemic proportions. This article discusses the etiology and treatment of hypertension in CKD so that it can be better controlled.

Concurrent treatment with an ACE inhibitor may amplify the utility of calcium supplementation for control of hypertension

Although supplemental calcium typically lowers blood pressure in subjects with salt-sensitive, low-renin hypertension - presumably by down-regulating increased production of parathyroid hormone (PTH) and/or parathyroid hypertensive factor (PHF) - its impact on the blood pressure of unselected hypertensive or normotensive subjects, as assessed by meta-analyses, appears to be trivial at best. This suggests that calcium may actually raise blood pressure a bit in some patients with high-renin hypertension, a prediction that is borne out in rodent models of this disorder. There is limited clinical evidence that long-term calcium supplementation tends to raise plasma renin activity; this finding, if valid, could evidently rationalize the equivocal clinical impact of calcium on blood pressure. Salt restriction likewise boosts renin production, and this effect tends to most notable in subjects whose blood pressure fails to decline during low-salt diets. Two clinical groups have demonstrated that salt restriction has a larger and more consistently beneficial impact on the blood pressure of hypertensives when they concurrently are treated with ACE inhibitors - evidently because the physiological impact of the associated rise in renin is blunted. Analogous logic suggests that calcium supplementation may be more beneficial for hypertensives in the context of ACE inhibition or blockade of angiotensin II receptors; this supposition that can readily be tested clinically. The imminent availability of safe nutraceutical ACE inhibitors may make it more feasible for the general public to benefit from these therapeutic/preventive possibilities.

Nutritional modulation of parathyroid hormone secretion may influence risk for left ventricular hypertrophy

Recent studies demonstrate low serum levels of 25-hydroxyvitamin D in patients with congestive heart failure (CHF). Although this may in part reflect reduced capacity for outdoor exercise, the possibility that poor vitamin D status increases risk for left ventricular hypertrophy (LVH), and its common sequel CHF, merits consideration. In cardiomyocytes, hormones which activate protein kinase C (PKC) -- including norepinephrine, angiotensin II, and endostatin, implicated in the pathogenesis of LVH -- induce a hypertrophic response analogous to that seen in LVH. Transgenic mice overexpressing PKC-beta2 or its upstream activator Galphaq in cardiac myofibers develop a syndrome similar to LVH. Parathyroid hormone (PTH) also activates Galphaq and PKC in cardiomyocytes, and provokes the expected hypertrophic response. Both primary and secondary hyperparathyroidism are associated with high risk for LVH. Moreover, in uncomplicated essential hypertension, left ventricular mass index has been shown to correlate very tightly with serum PTH levels, independent of blood pressure. This latter finding suggests that variations of PTH within the normal range can influence induction of LVH in at-risk subjects. If so, nutritional and lifestyle measures which modulate PTH secretion may have an impact on LVH risk. PTH secretion should be down-regulated by good vitamin D status -- achieved through supplementation or regular uv exposure -- and by vegan diets moderately low in bioavailable phosphate. Although high calcium intakes can likewise suppress PTH, they also boost renin secretion, which could have a countervailing effect on risk for LVH. Whether these nutritional measures do indeed influence LVH risk could be examined in prospective studies targeting patients at high risk, such as hypertensives.

Angiotensin converting enzyme inhibition for cardiac hypertrophy in patients with end-stage renal disease: what is the evidence?

Dialysis patients show a high prevalence of cardiovascular complications among which left ventricular hypertrophy is one of the most frequent and is independently predictive of mortality. A recent study indicates that partial regression of left ventricular hypertrophy improves mortality and reduces cardiovascular events in end-stage renal disease (ESRD) patients, suggesting the importance of targeting therapeutic strategies to reduce cardiac hypertrophy and improve the outcome in these patients. The pathogenesis of left ventricular hypertrophy in ESRD patients is multifactorial and includes hypertension, activation of the renin-angiotensin system, increased sympathetic activity, chronic volume overload, chronic anaemia and hyperparathyroidism. In this paper, we review the available experimental and clinical evidence showing the important contribution of the renin-angiotensin system as well as its interaction with the sympathetic nervous system in the pathogenesis of left ventricular hypertrophy in ESRD patients. Furthermore, we summarize the results of currently available clinical studies that examined the effects of angiotensin-converting enzyme inhibition or angiotensin receptor antagonism on left ventricular hypertrophy in ESRD patients, and review evidences that support the use of angiotensin-converting enzyme inhibitors or angiotensin receptor antagonists in the ESRD population.

A moderately low phosphate intake may provide health benefits analogous to those conferred by UV light - a further advantage of vegan diets

Although exposure to ultraviolet light is often viewed as pathogenic owing to its role in the genesis of skin cancer and skin aging, there is growing epidemiological evidence that such exposure may decrease risk for a number of more serious cancers, may have a favorable impact on blood pressure and vascular health, and may help to prevent certain autoimmune disorders - in addition to its well-known influence on bone density. Most likely, these health benefits are reflective of improved vitamin D status. Increased synthesis or intake of vitamin D can be expected to down-regulate parathyroid hormone (PTH), and to increase autocrine synthesis of its active metabolite calcitriol in certain tissues; these effects, in turn, may impact cancer risk, vascular health, immune regulation, and bone density through a variety of mechanisms. Presumably, a truly adequate supplemental intake of vitamin D - manyfold higher than the grossly inadequate current RDA - could replicate the benefits of optimal UV exposure, without however damaging the skin. Diets moderately low in bioavailable phosphate - like many vegan diets - might be expected to have a complementary impact on disease risks, inasmuch as serum phosphate suppresses renal calcitriol synthesis while up-regulating that of PTH. A proviso is that the impact of dietary phosphorus on bone health is more equivocal than that of vitamin D. Increased intakes of calcium, on the other hand, down-regulate the production of both PTH and calcitriol - the latter effect may explain why the impact of dietary calcium on cancer risk (excepting colon cancer), hypertension, and autoimmunity is not clearly positive. An overview suggests that a vegan diet supplemented with high-dose vitamin D should increase both systemic and autocrine calcitriol production while suppressing PTH secretion, and thus should represent a highly effective way to achieve the wide-ranging health protection conferred by optimal UV exposure.

Lower risk for cardiovascular mortality in oral 1alpha-hydroxy vitamin D3 users in a haemodialysis population

BACKGROUND

Renal failure results in deficiency of active vitamin D3 that has diverse effects on metabolism and organ functions. Treatment with active forms of vitamin D(3) ameliorates abnormalities in bone and mineral metabolism, cardiac function, immune response and others. We hypothesized that treatment with vitamin D(3) may be beneficial for survival in patients with end-stage renal disease (ESRD).

METHODS

We compared the risk of death between regular users (n = 162) and non-users (n = 80) of oral 1alpha-hydroxyvitamin D3 (alfacalcidol) in a cohort of ESRD patients undergoing haemodialysis for a follow-up of 61 +/- 23 months. The daily dose of alfacalcidol ranged from 0.25 to 1.5 microg, with a median of 0.5 microg.

RESULTS

The alfacalcidol users showed a lower risk of death from cardiovascular disease than the non-users in a univariate Cox model [hazards ratio (HR) 0.287, 95% confidence interval (CI) 0.127-0.649, P = 0.003], whereas the risk for death from non-cardiovascular disease was not different between the two groups. Stepwise multivariate Cox analysis showed that cardiovascular mortality was significantly associated with age, presence of diabetes mellitus and treatment with alfacalcidol (HR 0.377, 95% CI 0.246-0.578, P = 0.022).

CONCLUSIONS

These results indicate that use of oral alfacalcidol was associated with reduced risk for cardiovascular death in this cohort of ESRD patients. The result of this observational study warrants further randomized controlled trials with 1alpha-hydroxy vitamin D3 to confirm the possibility that such medication improves survival of ESRD patients.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.

ACE inhibitors and survival of hemodialysis patients

BACKGROUND

Cardiovascular disease is a leading cause of death in patients with end-stage renal disease (ESRD). Hypertension is a major risk factor for cardiovascular complications in these patients. Angiotensin-converting enzyme (ACE) inhibitors are an effective treatment for hypertension in patients with ESRD and are known to improve prognosis in patients with chronic renal failure. We investigated their effect on mortality in patients undergoing long-term hemodialysis therapy.

METHODS

Clinical data for patients on hemodialysis therapy between 1994 and 2000 were reviewed. Patients were grouped according to whether they had been treated with ACE inhibitors.

RESULTS

Sixty patients had been treated with ACE inhibitors (treated group) and 66 patients had not (untreated group). Blood pressure reduction was not significantly different between the treated and untreated groups. Nevertheless, comparing the treated group with the untreated group, mortality was decreased significantly in the treated group, with a risk reduction of 52% (rate ratio [RR], 0.482; confidence interval [CI], 0.25 to 0.91; P < 0.0019). In treated patients 65 years or younger, the absolute risk reduction of mortality was 79% (RR, 0.211; CI, 0.08 to 0.58; P < 0.0006).

CONCLUSION

Although further research is needed, these preliminary findings suggest that ACE inhibitors, independently of their antihypertensive effect, may dramatically reduce mortality among chronic hemodialysis patients 65 years or younger.

Intracellular free calcium in the neutrophils of maintenance haemodialysis patients

Chronic renal failure has on occasion been referred to as a state of calcium toxicity. The aim of this study was to investigate the status of intracellular free Ca2+ in the neutrophils of chronic renal failure patients on maintenance haemodialysis treatment. Factors previously suggested to influence intracellular free Ca2+ were investigated including PTH levels, oxidative stress and recombinant human erythropoietin administration. The study involved 14 chronic renal failure patients on the haemodialysis programme of the Pretoria Academic hospital. Intracellular free Ca2+ and transmembrane Ca2+ fluxes were investigated by fluorescence spectrophotometry. Increases above control values were found in intracellular free Ca2+ (P-value 0.0242) and in the transmembrane Ca2+ flux upon fMLP stimulation (P-value 0.0002). The results showed significant differences in intracellular free Ca2+ between patients on rHuEPO and patients not on rHuEPO. The apparently rHuEPO-induced increase in intracellular free Ca2+ persisted in the presence of calcium channel blockers. No overt indications of oxidative stress could be detected by the antioxidant vitamin levels. It is concluded that factors other than those associated with uraemia, such as rHuEPO administration, might contribute to the often reported increase in intracellular free Ca2+ in these patients. Further studies to investigate the relationship between intracellular free Ca2+, rHuEPO and calcium channel blockers are suggested.

Calcium channel blocker use and mortality among patients with end-stage renal disease

BACKGROUND

Patients on dialysis suffer from alarming rates of cardiovascular disease. While calcium channel blockers (CCBs) are prescribed widely to patients with end-stage renal disease (ESRD) for the treatment of hypertension, the long-term outcomes associated with the use of these medications are not known. We sought to determine the association between CCB use and mortality among a cohort of ESRD patients.

METHODS

Data were utilized from the United States Renal Data System Dialysis Morbidity and Mortality Wave II, a randomly selected prospective cohort of 4065 ESRD patients who began dialysis in 1996. Clinical data, including medication information, were collected 60 days after the start of dialysis. Subsequent survival status and cause of death were ascertained. The Cox proportional hazards model was used to estimate the relative risk of death associated with CCB use.

RESULTS

Data from 3716 patients (91.4%) were available for analysis. Fifty-one percent of the study patients were prescribed a CCB. The use of a CCB was associated with a 21% lower risk of total mortality (RR 0.79, CI 0.69 to 0.90) and a 26% lower risk of cardiovascular specific mortality (RR 0.74, CI 0.60 to 0.91). For patients with pre-existing cardiovascular disease, CCB use was associated with a 23% (RR 0.77, CI 0.65 to 0.91) and 32% (RR 0.68, CI 0.53 to 0.87) lower risk of total and cardiovascular mortality, respectively.

CONCLUSION

After controlling for known risk factors and potential confounders, CCBs were found to be associated with a lower risk of mortality among ESRD patients.

Hemodialysis-associated hypertension: pathophysiology and therapy

The majority of end-stage renal disease (ESRD) patients are hypertensive. Hypertension in the hemodialysis patient population is multifactorial. Further, hypertension is associated with an increased risk for left ventricular hypertrophy, coronary artery disease, congestive heart failure, cerebrovascular complications, and mortality. Antihypertensive medications alone do not adequately control blood pressure (BP) in hemodialysis patients. There are, however, several therapeutic options available to normalize BP in these patients, often without the need for additional drug therapy (eg, long, slow hemodialysis; short, daily hemodialysis; nocturnal hemodialysis; or, most effectively, dietary salt and fluid restriction in combination with reduction of dialysate sodium concentration). Optimal BP in dialysis patients is not different from recommendations for the general population, even though definite evidence is not yet available. Predialysis systolic and diastolic BPs are of particular importance. Left ventricular mass correlates with predialysis systolic BP. Survival is better in hemodialysis patients with a mean arterial pressure below 99 mm Hg as compared with those with higher BP. Low predialysis systolic BP (<110 mm Hg) and low predialysis diastolic BP (<70 mm Hg) are associated with increased mortality, primarily because of severe congestive heart failure or coronary artery disease. Patients that experience repeated intradialytic hypotensive episodes should also be viewed with caution, and predialytic BP values should be reevaluated. A possible treatment option for these patients may be slow, long hemodialysis; short, daily hemodialysis; or nocturnal hemodialysis. Among the antihypertensive agents currently available, angiotensin-converting enzyme (ACE) inhibitors appear to have the greatest ability to reduce left ventricular mass. Pressure load can be satisfactorily determined by using the average value of predialysis BP measurements over 1 month. In selected hemodialysis patients, interdialytic ambulatory blood pressure monitoring (ABPM) may help to determine if the patient is in fact hypertensive. In addition, ABPM provides important information about the change in BP between day and night. Regular home BP monitoring, yearly echocardiography, and treatment of traditional risk factors for cardiovascular disease are recommended.

Hypertension in hemodialysis patients

Hypertension is very common and often poorly controlled in patients undergoing chronic hemodialysis. While high blood pressure has been documented to adversely impact several intermediate outcomes of cardiovascular disease, whether hypertension is an independent risk factor for mortality in this population is not clear. Expansion of extracellular fluid volume is the major pathophysiologic mechanism for the development of hypertension in these patients; however, alterations in other humoral mechanisms also play a significant role. Optimization of volume status is, therefore, the cornerstone of therapy with additional use of antihypertensive medications as needed. Good quality prospective studies are urgently needed to define the measurement techniques and blood pressure goals, and to develop therapeutic strategies for more effective management of hypertension in this high-risk population.

Determinants of mean arterial pressure and pulse pressure in chronic haemodialysis patients

Hypertension is highly prevalent in the dialysis population, and has been implicated in the pathogenesis of the observed excess of cardiovascular morbidity and mortality in these patients. Nevertheless, there are no reports on the clinical and biochemical determinants of both pulse pressure (PP) and mean arterial pressure (MAP) in dialysis populations. A total of 541 haemodialysed patients from 11 dialysis centres were included in the study. The demographic, clinical, and biological characteristics were recorded. Both pre- and post- dialytic blood pressures (systolic and diastolic) were measured. PP and MAP were calculated. Mean predialytic PP was 67 +/- 17 mm Hg and significantly decreased after dialysis (60 +/- 18 mm Hg; P < 0.0001). In multivariate analysis, a 10 mm Hg increase in PP was positively associated with age (RR, 2.01; 95% CI, 1.35-5.01, for a 10-year increase in age), diabetes mellitus (RR, 1.08; 95% CI, 1.04-1.14), interdialytic weight gain (IWG) (RR, 1.84; 95% CI, 1.07-3.18, for 1% increase in IWG), and current smoking (RR, 2.59; 95% CI, 1.13-5.92) and negatively with Hb concentration (RR, 0.92; 95% CI, 0.84-0.99, for a 1 g/100 ml in Hb). Mean predialytic MAP was 98 +/- 15 mm Hg and significantly decreased after dialysis (91 +/- 16 mm Hg; P < 0.0001). In multivariate analysis, a 10 mm Hg increase in MAP was positively associated with parathyroid hormone (PTH) (RR, 1.32; 95% CI, 1.15-1.6, for 50 ng/ml in PTH), erythropoietin (EPO) treatment (RR, 1.09; 95% CI, 1.03-1.16), and current smoking (RR, 1.87; 95% CI, 1.39-2.41). PP and MAP are associated with different clinical parameters. Most of these factors are potentially reversible. Smoking cessation, correction of anaemia and limitation of IWG should be important challenges for physicians in care of dialysis patients.

Risk-benefit ratio of angiotensin antagonists versus ACE inhibitors in end-stage renal disease

The effective treatment of hypertension is an extremely important consideration in patients with end-stage renal disease (ESRD). Virtually any drug class--with the possible exception of diuretics--can be used to treat hypertension in the patient with ESRD. Despite there being such a wide range of treatment options, drugs which interrupt the renin-angiotensin axis are generally suggested as agents of choice in this population, even though the evidence in support of their preferential use is quite scanty. ACE inhibitors, and more recently angiotensin antagonists, are the 2 drug classes most commonly employed to alter renin-angiotensin axis activity and therefore produce blood pressure control. ACE inhibitor use in patients with ESRD can sometimes prove an exacting proposition. ACE inhibitors are variably dialysed, with compounds such as catopril, enalapril, lisinopril and perindopril undergoing substantial cross-dialyser clearance during a standard dialysis session. This phenomenon makes the selection of a dose and the timing of administration for an ACE inhibitor a complex issue in patients with ESRD. Furthermore, ACE inhibitors are recognised as having a range of nonpressor effects that are pertinent to patients with ESRD. Such effects include their ability to decrease thirst drive and to decrease erythropoiesis. In addition, ACE inhibitors have a unique adverse effect profile. As is the case with their use in patients without renal failure, use of ACE inhibitors in patients with ESRD can be accompanied by cough and less frequently by angioneurotic oedema. In the ESRD population, ACE inhibitor use is also accompanied by so-called anaphylactoid dialyser reactions. Angiotensin antagonists are similar to ACE inhibitors in their mechanism of blood pressure lowering. Angiotensin antagonists are not dialysable and therefore can be distinguished from a number of the ACE inhibitors. In addition, the adverse effect profile for angiotensin antagonists is remarkably bland, with cough and angioneurotic oedema rarely, if ever, occurring. In patients with ESRD, angiotensin antagonists are also not associated with the anaphylactoid dialyser reactions which occur with ACE inhibitors. The nonpressor effects of angiotensin antagonists--such as an influence on thirst drive and erythropoiesis--have not been explored in nearly the depth, as they have been with ACE inhibitors. Although ACE inhibitors have not been compared directly to angiotensin antagonists in patients with ESRD, angiotensin antagonists possess a number of pharmacokinetic and adverse effect characteristics, which would favour their use in this population.

Parathyroid hormone, vitamin D, and cardiovascular disease in chronic renal failure

BACKGROUND

Parathyroid hormone and vitamin D have been shown to influence cardiac and vascular growth and function experimentally in human subjects with normal renal function. Because of the increased prevalence of hyperparathyroidism and altered vitamin D status in chronic renal failure, these alterations have been considered to contribute to the increased prevalence of cardiovascular disease and hypertension seen in this patient population. Methods and Results. In this article, we review experimental and clinical literature on the cardiovascular effects of parathyroid hormone and vitamin D and relate them to the development of cardiac and vascular dysfunction in uremia, such as: cardiomyopathy, myocardial hypertrophy, and fibrosis, as well as to myocardial ischemia; uremic glucose intolerance, dyslipidemia, and atherosclerosis; hypertension; and vascular and cardiac calcifications.

CONCLUSIONS

The hyperparathyroid state and altered vitamin D status found in uremia contribute to the cardiovascular pathology seen clinically in uremia and also to the excess mortality from cardiovascular causes found in this patient group. The therapeutic implications of these observations are also discussed.

Impaired lymphocyte calcium metabolism in end-stage renal disease: enhanced influx, decreased efflux, and reduced response to mitogen

Lymphocytes from patients with end-stage renal disease (ESRD) exhibit elevated cytosolic calcium concentration ((Ca2+)i), but the mechanisms responsible for this elevated (Ca2+)i have not been entirely elucidated. In addition, lymphocyte proliferative responses to mitogenic stimuli are suppressed in patients with ESRD. The objectives of the study were as follows: (1) to measure calcium influx and efflux in lymphocytes from patients with ESRD; (2) to measure the effect of the calcium regulator parathyroid hormone (PTH) on lymphocyte (Ca2+)i; (3) to measure cytosolic calcium signal in patients' lymphocytes after mitogenic stimulation. The three study groups were as follows: healthy subjects (control), patients with chronic renal failure (CRF) before the beginning of regular dialysis treatment, and patients undergoing regular hemodialysis (HD) treatment. Peripheral blood lymphocytes were tested in vitro for (Ca2+)i, Ca2+ influx, and membrane calcium-adenosine triphosphatase (CaATPase) activity. Cytosolic Ca2+ signals were traced after stimulations by PTH and by phytohemagglutinin (PHA). Baseline (Ca2+)i was significantly elevated in both ESRD groups. Ca2+ influx was enhanced and CaATPase activity was reduced in both ESRD groups. PTH caused a (Ca2+)i increase in normal cells in a dose-dependent manner. PHA caused a (Ca2+)i elevation, with a Ca2+ signal in both groups of patients with ESRD that was significantly smaller than that in the control group. These findings suggest that the high (Ca2+)i found in lymphocytes from patients with ESRD is the result of enhanced Ca2+ influx concomitant with reduced Ca2+ extrusion, as reflected by reduced CaATPase activity. The patients' elevated serum PTH levels may have contributed to the high (Ca2+]i. The impaired cytosolic (Ca2+)i response to PHA may explain in part the suppressed lymphocyte proliferative response to PHA in patients with ESRD.

Influence of nycthemeral blood pressure pattern in treated hypertensive patients on hemodialysis

Arterial hypertension in end-stage renal disease (ESRD) patients is characterized by an altered nycthemeral blood pressure (BP) rhythm and an increased pulse pressure, and it could be suggested that this association of risk factors plays a major role in the cardiovascular prognosis of this population. The aim of this study was to determine the influence of nycthemeral BP pattern on arterial distensibility and pulsatile components of BP in treated hypertensive patients on regular hemodialysis. Forty-two hypertensive patients were included, and all underwent ambulatory BP and pulse wave velocity (PWV) measurements between the femoral and carotid arteries. The patients were divided into two groups according to the magnitude of the nocturnal fall in BP: dippers and non-dippers. The groups were similar in gender, age, duration of hemodialysis, body mass index, body size, history of cardiovascular complications, class and number of antihypertensive drugs used per patient. PWV was significantly higher in non-dippers. For the whole population, a stepwise regression analysis showed that PWV and erythropoietin therapy were independently related to the impaired nycthemeral BP pattern. In addition to its pressor effect, erythropoietin could have a deleterious influence on the ambulatory BP profile of treated hypertensive patients in ESRD. Arterial distensibility and nycthemeral BP impairment are linked, and these cardiovascular risk factors should be taken into account together for the management of hypertensive hemodialysis patients.

Use of the medical differential diagnosis to achieve optimal end-stage renal disease outcomes

Compared with the general population, end-stage renal disease (ESRD) patients continue to have a higher than expected morbidity and mortality. Hypoalbuminemia, anemia, hypertension, and inadequate dialysis are all thought to contribute to the high morbidity and mortality among ESRD patients. Anemia algorithms should help to standardize the approach to anemia and the use of recombinant human erythropoietin (rHuEPO), but clinicians still must review each patient individually, searching for and treating the multitude of interrelated factors that affect rHuEPO responsiveness. Hypoalbuminemia is a very strong predictor of increased morbidity and mortality in dialysis and nondialysis patients. The causes of hypoalbuminemia are multifactorial, and diagnosis of the cause of hypoalbuminemia is usually elusive. The basis of the poorer survival in US dialysis patients remains controversial, but inadequate dialysis has been implicated. To assure adequate dialysis, the dialysis prescription must be individualized for each patient, and delivered dialysis must be routinely monitored. Hypertension is associated with left ventricular hypertrophy, which is also an important determinant of survival in ESRD patients. Hypertension should be treated in ESRD patients in conjunction with other interventions that are known to reverse left ventricular hypertrophy. Special efforts must be made in the medical management of hypoalbuminemia, anemia, hypertension, and dialysis treatment adequacy to improve survival in patients with ESRD.

Intracellular calcium and blood pressure: comparison between primary hyperparathyroidism and essential hypertension

Intracellular calcium has been reported to be increased in essential hypertension, and thought to play a role in its genesis through facilitation of vascular smooth muscle contraction. Since hypertension is more prevalent in primary hyperparathyroidism, intracellular calcium may also be increased in this condition. To investigate whether the hyperparathyroid condition, i.e., hypercalcemia and increased PTH per se, could be associated with high intracellular calcium, we measured intracellular calcium in platelets with the Quin-2 AM fluorometric method in 11 normotensive patients with primary hyperparathyroidism, 15 patients with essential hypertension, and 18 normal controls, all matched for age and sex. We repeated the measurements in 9 of the hyperparathyroid patients after successful surgery. We found that intracellular calcium was higher in normotensive patients with primary hyperparathyroidism than in normal controls (198 +/- 24 vs 113 +/- 11 nM, p < 0.05), but lower than in patients with essential hypertension (198 +/- 24 vs 286 +/- 38 nM, p < 0.05). Successful removal of a parathyroid adenoma decreased intracellular calcium from 215 +/- 22 to 116 +/- 19 nM, (p < 0.01). In the patients with primary hyperparathyroidism, intracellular calcium was strongly correlated with the levels of PTH (r = 0.87, p < 0.01), but not with the total serum calcium levels (r = 0.04, NS). The decrease in intracellular calcium after parathyroidectomy was also strongly correlated with the decrease in PTH (r = 0.84, P < 0.01), but not with the decrease in total serum calcium (r = 0.16, NS). In the patients with essential hypertension, intracellular calcium correlated well with systolic (r = 0.69, p < 0.01), diastolic (r = 0.76, p < 0.01) and especially mean arterial pressure (r = 0.86, P < 0.01). There was no correlation between blood pressure and intracellular calcium in the patients with primary hyperparathyroidism. We conclude that normotensive patients with primary hyperparathyroidism, as well as patients with essential hypertension, can have increased concentrations of intracellular calcium in platelets. The correction of the hyperparathyroid condition normalizes intracellular calcium concentration. The close correlation between PTH and intracellular calcium suggests that PTH may act as a ionophore for calcium entry into cells. Whether the increased levels of intracellular calcium may reflect a pre-hypertensive condition in normotensive patients with primary hyperparathyroidism remains to be determined.

Verapamil reverses abnormal [Ca2+]i and carbohydrate metabolism of PMNL of dialysis patients

The basal levels of cytosolic calcium ([Ca2+]i) of polymorphonuclear leukocytes (PMNL) are elevated in hemodialysis (HD) patients, and this abnormality has been implicated in the dysfunction of the PMNL of these patients. The elevated [Ca2+]i appears to be due to PTH-induced entry of calcium into PMNL, an action that may be prevented by calcium channel blockers. We examined [Ca2+]i and carbohydrate metabolism of PMNL of normal subjects and of HD patients before, after eight to nine weeks of verapamil therapy (120 mg/day), and after eight to ten weeks of discontinuation of verapamil treatment. In HD patients, the basal levels of [Ca2+]i of PMNL are elevated and their glucose uptake, the activity of total and active forms of glycogen synthetase, and glycogen content are reduced compared to values in normal subjects (P < 0.01). These derangements were normalized after verapamil therapy and re-emerged after discontinuation of treatment with verapamil despite no change in blood levels of PTH. The results indicate that the elevation in [Ca2+]i of PMNL and the consequent derangements in carbohydrate metabolism of these cells are treatable with a calcium channel blocker. The data assign a valuable role for calcium channel blockers for the amelioration of some aspects of cell dysfunction of uremia.

Profound reversible CD4+ T lymphocytopenia in a severely uremic patient

We report a human immunodeficiency virus antibody-negative, profoundly uremic patient who presented with a CD4+ T lymphocyte count of 133/mm3, a CD8+ T lymphocyte count of 77/mm3, and a CD3+ T lymphocyte count of 259/mm3. These values decrease significantly below reported levels in other lymphopenic uremic patients. High-efficiency chronic hemodialysis resulted in correction of these cytopenias to a normal range within 12 weeks.

Altered cytosolic calcium homeostasis in rat cardiac myocytes in CRF

Chronic renal failure (CRF) is associated with an increase in calcium content of heart. This was attributed to the secondary hyperparathyroidism of CRF, since PTH augments entry of calcium into cardiac myocytes. At present, it is not known whether the increase in calcium content of heart reflects a rise in basal levels of cytosolic calcium ([Ca2+]) of cardiac myocytes. Further, in order for the PTH-induced entry of calcium into cardiac myocytes to raise their basal levels of [Ca2+]i, calcium extrusion out of these cells should be impaired as well. The present study examined the effect of CRF with and without excess PTH (PTX) and of the treatment of CRF rats with verapamil on basal levels of [Ca2+]i and ATP content of cardiac myocytes and on the activities of the pumps that are directly (Ca(2+)-ATPase and Na(+)-Ca2+ exchanger) and indirectly (Na(+)-K+ ATPase) responsible for calcium extrusion out of these cells. The basal levels of [Ca2+]i of cardiac myocytes increased (P < 0.01) and their ATP content decreased (P < 0.01) as the duration of CRF advanced. CRF was associated with significant decrement in Vmax of Ca2+ ATPase and Na(+)-K+ ATPase and in Na(+)-Ca2+ exchange. These derangements were prevented by prior PTX of the CRF rats or by their treatment with verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)