Vasopressin as vasopressor

Diabetes Insipidus after Vasopressin Withdrawal: A Scoping Review

Objectives

The objective of this study is to synthesize the current literature about the relationship between the occurrence of diabetes insipidus (DI), its diagnosis criteria, and management after withdrawal of vasopressin (VP) in critically ill.

Data sources

This scoping review followed the recommendations of Preferred Reporting Items for Systematic Review and Meta-Analyses for Scoping Review (PRISMA-ScR). The search literature was conducted in MEDLINE and EMBASE databases, until March 2022. A manual search was also conducted in order to include articles that were not identified in the initial search performed in the databases.

Study selection and data extraction

The selection of studies and extraction of data were carried out in a paired and independent manner. There was no restriction regarding the language of publication of the included manuscripts.

Data synthesis

The analysis included 17 studies (16 case reports and one retrospective cohort). All studies used VP, with a median time of drug infusion of 48 hours (IQR: 16-72) and DI incidence of 1.53%. The diagnosis of DI was based on diuresis output and concomitant hypernatremia or changes in serum sodium concentration, with median time to symptoms onset after discontinuation of VP of 5 hours (IQR: 3-10). The treatment of DI consisted mainly of fluid management and the use of desmopressin.

Conclusions

DI after VP withdrawal was present in 51 patients described in 17 studies, but diagnosis and management varied among each report. Using the available data, we propose a diagnosis suggestion and a flowchart for managing patients with DI after withdrawal of VP in the Intensive Care Unit. Multicentric collaborative research is urgently needed to obtain more quality data on this topic.

How to cite this article

Pérsico RS, Viana MV, Viana LV. Diabetes Insipidus after Vasopressin Withdrawal: A Scoping Review. Indian J Crit Care Med 2022;26(7):846-852.

Anticancer Medications and Sodium Dysmetabolism

Therapeutic advances have revolutionised cancer treatment over the last two decades, but despite improved survival and outcomes, adverse effects to anticancer therapy such as dyselectrolytaemias do occur and need to be managed appropriately. This review explores essential aspects of sodium homeostasis in cancer with a focus on alterations arising from anticancer medications. Sodium and water balance are tightly regulated by close interplay of stimuli arising from hypothalamic osmoreceptors, arterial and atrial baroreceptors and the renal juxtaglomerular apparatus. This delicate balance can be disrupted by cancer itself, as well as the medications used to treat it. Some of the conventional chemotherapeutics, such as alkylating agents and platinum-based drugs, can cause hyponatraemia and, on rare occasions, hypernatraemia. Other conventional agents such as vinca alkaloids, as well as newer targeted cancer therapies including small molecule inhibitors and monoclonal antibodies, can cause hyponatraemia, usually as a result of inappropriate antidiuretic hormone secretion. Hyponatraemia can also sometimes occur secondarily to drug-induced hypocortisolism or salt-wasting syndromes. Another atypical but distinct mechanism for hyponatraemia is via pituitary dysfunction induced by immune checkpoint inhibitors. Hypernatraemia is uncommon and occasionally ensues as a result of drug-induced nephrogenic diabetes insipidus. Identification of the aetiology and appropriate management of these conditions, in addition to averting treatment-related problems, can be lifesaving in critical situations.

Effect of increased water intake on plasma copeptin in patients with chronic kidney disease: results from a pilot randomised controlled trial

OBJECTIVES

Increased water intake may have a beneficial effect on the kidney through suppression of plasma vasopressin. We examined the effect of increased water intake on plasma copeptin (a marker of vasopressin) over 6 weeks in patients with chronic kidney disease.

DESIGN

Secondary analysis of a randomised controlled parallel-group pilot trial.

SETTING

Canada, 2012-2013.

PARTICIPANTS

28 patients with stage 3 chronic kidney disease randomised (2:1) to a hydration (n=17) or control group (n=11).

INTERVENTION

The hydration group was coached to increase water intake by up to 1.5 L/day for 6 weeks. The control group was asked to maintain regular water intake.

MEASURES AND OUTCOMES

Participants provided blood and 24 h urine samples at baseline and 6 weeks. Change in plasma copeptin was compared within and between study groups.

RESULTS

Participants were 64% male with a mean age of 62 years and an estimated glomerular filtration rate of 40 mL/min/1.73 m(2). Between baseline and 6 weeks, 24 h urine volume increased by 0.7 L/day in the hydration group, rising from 2.3 to 3.0 L/day (p=0.01), while decreasing by 0.3 L/day among controls, from 2.0 to 1.7 L/day (p=0.07); between-group difference: 0.9 L/day (95% CI 0.37 to 1.46; p=0.002). In the hydration group, median copeptin decreased by 3.6 pmol/L, from 15.0 to 10.8 pmol/L (p=0.005), while remaining stable among controls at 19 pmol/L (p=0.76; p=0.19 for the between-group difference in median change); the between-group difference in mean change was 5.4 pmol/L (95% CI -1.2 to 12.0; p=0.11).

CONCLUSIONS

Adults with stage 3 chronic kidney disease can be successfully randomised to drink approximately 1 L more per day than controls. This increased water intake caused a significant decrease in plasma copeptin concentration. Our larger 12-month trial will examine whether increased water intake can slow renal decline in patients with chronic kidney disease.

TRIAL REGISTRATION NUMBER

NCT01753466.

Copeptin as a biomarker in heart failure

Increased neurohormonal activation is a key feature of heart failure (HF). Copeptin is a surrogate marker for proarginine vasopressin and the prognostic value of copeptin has been reported for multiple disease states of both nonvascular and cardiovascular etiology. Elevated plasma copeptin in HF has been associated with adverse outcomes such as increased mortality, risk of hospitalization and correlates with the severity of HF. Copeptin may add prognostic information to already established predictors such as clinical variables and natriuretic peptides in HF. In addition, copeptin has been found to be a superior marker when compared with BNP and NT-proBNP in HF patients discharged after hospitalization caused by HF or myocardial infarction (MI). The optimal use of copeptin in HF remains unresolved and future appropriately sized and randomized trials must determine the role of copeptin in HF as a marker of adverse outcomes, risk stratification or as a target in biomarker-guided therapy with arginine vasopressin-antagonists in individualized patient treatment and everyday clinical practice.

Pharmacological strategy designed to limit ischemia-reperfusion injury in brain dead donor kidneys

Ischemia-reperfusion injury is a complex physiological process responsible for delayed renal function or primary graft non-function, explicitly when kidney allograft are issued from expanded criteria donor. The purpose of this review is to detail the detrimental phenomenons altering kidney allograft's integrity in brain dead donor, therefore suggesting pharmacological interventions aiming to reduce ischemia-reperfusion injuries and improving transplantation outcome. This ischemia-reperfusion phenomenon must therefore be anticipated through the whole procedure starting at the stage of conditioning of the potential donor. Hormonal and haemodynamic consequences of brain death modify perfusion and oxygenation conditions of the organs Thus, after describing the autonomic, metabolic, endocrine and chemokine storm occurring during brain death, the authors focus on strategies to prevent hemodynamic instability in the donor and to limit the consequences of hormonal and immunological changes on organs that will eventually be transplanted.

Copeptin (C-terminal pro arginine-vasopressin) is an independent long-term prognostic marker in heart failure with reduced ejection fraction

BACKGROUND

The level of copeptin, a stable fragment of pro-arginine-vasopressin (AVP), correlates with disease severity. It is an established, short-term prognostic marker for patients with heart failure with reduced ejection fraction (HFREF). We aimed to examine the association between copeptin and long-term mortality. We also studied the clinical usefulness of copeptin as a prognostic biomarker by analysing the improvement of net reclassification.

METHODS

Copeptin concentrations were measured in a cohort of 195 consecutive patients with HFREF. Disease severity and clinical parameters were determined at baseline, and all-cause mortality was recorded after five-year follow-up.

RESULTS

One hundred and ten patients died during the five-year follow-up (five-year mortality rate: 0.56). Univariate analysis identified copeptin (HR 2.168 [95% CI 1.740-2.700]) as a predictor of mortality. The final, multivariable Cox survival model identified a number of independent predictors of death. These included higher NHYA functional class, previous MI, at least one hospitalisation for worsening HF (within the two years before inclusion into the study), elevated blood urea nitrogen, NT-proBNP-, and copeptin levels, as well as increased red blood cell distribution width, and decreased GFR. The addition of copeptin alone to the baseline predictive model (NT-proBNP only) resulted in a minor (8.21%) improvement, whereas the final, multivariable model showed a significant increase in net reclassification (10.26%, p=0.015).

CONCLUSIONS

These data indicate that copeptin is an independent long-term prognostic marker in HFREF, with possible clinical relevance for multimarker risk prediction algorithms.

β-adrenergic receptor-mediated cardiac contractility is inhibited via vasopressin type 1A-receptor-dependent signaling

BACKGROUND

Enhanced arginine vasopressin levels are associated with increased mortality during end-stage human heart failure, and cardiac arginine vasopressin type 1A receptor (V1AR) expression becomes increased. Additionally, mice with cardiac-restricted V1AR overexpression develop cardiomyopathy and decreased β-adrenergic receptor (βAR) responsiveness. This led us to hypothesize that V1AR signaling regulates βAR responsiveness and in doing so contributes to development of heart failure.

METHODS AND RESULTS

Transaortic constriction resulted in decreased cardiac function and βAR density and increased cardiac V1AR expression, effects reversed by a V1AR-selective antagonist. Molecularly, V1AR stimulation led to decreased βAR ligand affinity, as well as βAR-induced Ca(2+) mobilization and cAMP generation in isolated adult cardiomyocytes, effects recapitulated via ex vivo Langendorff analysis. V1AR-mediated regulation of βAR responsiveness was demonstrated to occur in a previously unrecognized Gq protein-independent/G protein receptor kinase-dependent manner.

CONCLUSIONS

This newly discovered relationship between cardiac V1AR and βAR may be informative for the treatment of patients with acute decompensated heart failure and elevated arginine vasopressin.

Increased urine aquaporin-2 relative to plasma arginine vasopressin is a novel marker of response to tolvaptan in patients with decompensated heart failure

BACKGROUND

Preserved function of the renal collecting duct may be essential for response to the vasopressin V2receptor antagonist, tolvaptan (TLV), but the predictors of response to TLV are unknown. METHODS AND RESULTS: Sixty consecutive patients with stage D decompensated heart failure (HF) who had received TLV on a de novo basis were retrospectively enrolled (TLV(+) group). Among them, 41 patients were responders defined according to urine volume (UV) increase after TLV initiation. In the UV-defined responders, plasma arginine vasopressin (P-AVP) had a close correlation with urine aquaporin-2 (U-AQP2; 5.42±3.54 ng/ml; r=0.843, P<0.001). In contrast, 19 were UV-defined non-responders, and they had extremely low U-AQP2 (0.76±0.59 ng/ml, P<0.001 vs. responders) regardless of P-AVP level. On receiver operating characteristic analysis, U-AQP2/P-AVP ≥0.5×10(3)clearly separated the UV-defined responders from the non-responders. We then identified AQP-defined responders as having U-AQP2/P-AVP ≥0.5×10(3). Sixty propensity score-matched HF patients without TLV treatment were examined, and exactly the same number of patients as that of the AQP-defined responders (n=41) was selected. These patients had a poorer survival without TLV than the TLV-treated responders during a 2-year observation period (73.8% vs. 94.8%, P=0.034).

CONCLUSIONS

U-AQP2/P-AVP is a novel predictor of response to TLV in patients with decompensated HF. AQP-defined responders may have a better prognosis on TLV treatment.

Dialysis hypotension: a role for inadequate increase in arginine vasopressin levels? A systematic literature review and meta-analysis

BACKGROUND

Intradialytic hypotension is a common complication of hemodialysis (HD). Some studies have suggested that inadequate arginine vasopressin (AVP) increase could play a role in the pathogenesis of intradialytic hypotension. However, AVP levels during HD and its relation to hypotension has never been systematically studied.

SUMMARY

PubMed and Embase were searched (1970-2013, search terms 'vasopressin' and 'hemodialysis') for studies reporting on AVP levels during standard HD or other dialysis techniques. Observational studies reporting on AVP levels pre- and postdialysis were additionally included in a meta-analysis. Thirty-seven studies were included in the systematic literature review, of which 26 studies were eligible for meta-analysis. The main findings were that pretreatment AVP levels were higher in dialysis patients compared with healthy controls (6.4 ± 3.5 vs. 2.5 ± 1.3 pg/ml, p = 0.003) and that plasma AVP levels showed little or no increase during HD (from 7.0 ± 4.9 to 8.8 ± 9.3, p = 0.433). Significant heterogeneity was found between studies. Meta-regression analysis revealed no significant associations between AVP and patient or study characteristics. Studies on other dialysis techniques showed mixed results regarding the AVP course. The eight studies that addressed the relation between intradialytic hypotension and AVP also showed inconsistent results.

KEY MESSAGES

Plasma AVP levels are higher in dialysis patients compared with healthy controls, but show little or no increase during HD. The lack of a rise in AVP levels during HD may be pathophysiologically involved in the onset of intradialytic hypotension, but firm conclusions are not possible from our review of the literature.

Copeptin, a surrogate marker for arginine vasopressin, is associated with cardiovascular and all-cause mortality in patients with type 2 diabetes (ZODIAC-31)

OBJECTIVE

Copeptin, a surrogate marker for arginine vasopressin, has been associated with cardiovascular (CV) events and mortality in patients with type 2 diabetes complicated by end-stage renal disease or acute myocardial infarction. For stable outpatients, these associations are unknown. Our aim was to investigate whether copeptin is associated with CV and all-cause mortality in patients with type 2 diabetes treated in primary care.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes participating in the observational Zwolle Outpatient Diabetes Project Integrating Available Care (ZODIAC) study were included. Cox regression analyses with age as time scale were used to assess the relationship of baseline copeptin with CV and all-cause mortality.

RESULTS

We included 1,195 patients (age 67±12 years, 44% male). Median baseline copeptin concentration was 5.4 (interquartile range [IQR] 3.1-9.6) pmol/L. After a median follow-up of 5.9 (IQR 3.2-10.1) years, 345 patients died (29%), with 148 CV deaths (12%). Log2 copeptin was associated with CV (hazard ratio 1.17 [95% CI 0.99-1.39]; P=0.068) and all-cause mortality (1.22 [1.09-1.36]; P=0.001) after adjustment for age, sex, BMI, smoking, systolic blood pressure, total cholesterol to HDL ratio, duration of diabetes, HbA1c, treatment with ACE inhibitors and angiotensin receptor blockers, history of CV diseases, log serum creatinine, and log albumin to creatinine ratio; however, copeptin did not substantially improve risk prediction for CV (integrated discrimination improvement 0.14% [IQR -0.27 to 0.55%]) and all-cause mortality (0.77% [0.17-1.37%]) beyond currently used clinical markers.

CONCLUSIONS

We found copeptin to be associated with CV and all-cause mortality in patients with type 2 diabetes treated in primary care. Intervention studies should show whether the high CV risk in type 2 diabetes can be reduced by suppression of vasopressin, for example by reducing salt intake.

An exploratory panel of biomarkers for risk prediction in pulmonary hypertension: emerging role of CT-proET-1

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare, deadly condition. Although risk stratification is extremely important for assessment of prognosis and to guide therapy, there is lack of evidence concerning the role of novel biomarkers. In a pivotal study, we sought to comparatively investigate the predictive power of several new biomarkers in PAH.

METHODS

Patients with prevalent PAH were enrolled in the study protocol, which included clinical, functional and echocardiographic assessment. Blood samples were collected at baseline for determination of NT-proBNP, CT-proET-1, MR-proANP, MR-proADM, copeptin and troponin I. Patients were clinically followed-up up to 12 months for first occurrence of hospital admission due to PAH-related clinical worsening, heart/lung transplantation or all-cause mortality.

RESULTS

Among the 28 included patients the pre-specified end-point occurred in 8 (29% event rate). There were higher baseline levels of CT-proET-1, copeptin, MR-proANP, NT-proBNP and troponin I in patients who reached the composite end-point. They also had larger right atria. In multivariate Cox regression, CT-proET-1 was the only biomarker associated with increased hazard of reaching the primary composite end-point (hazard ratio per tertile increase = 10.1; 95% CI 2.0 to 50.6).

CONCLUSIONS

CT-proET-1 provided prognostic information independent of other biomarkers. Importantly, we have provided the first evidence that CT-proET-1 may be superior to commonly used biomarkers.

Association of copeptin with myocardial infarct size and myocardial function after ST segment elevation myocardial infarction

OBJECTIVE

To investigate the relationship between circulating plasma copeptin values and infarct size as well as myocardial function at baseline and 4 months after mechanical reperfusion for ST segment elevation myocardial infarction (STEMI).

DESIGN

Prospective observational cohort study.

SETTING

University Hospital of Innsbruck.

PATIENTS

54 patients with acute STEMI.

MAIN OUTCOME MEASURES

Correlation of plasma copeptin with infarct size as well as left ventricular ejection fraction (LVEF) and remodelling.

METHODS

Participants underwent contrast enhanced cardiac MRI at baseline and 4 months thereafter. Blood samples were drawn 2 days after the onset of symptoms. Copeptin values were determined by an immunofluorescent assay.

RESULTS

Copeptin concentrations (median 10.4 pmol/l, IQR 6.0-14.4) were associated with early and chronic infarct size (r=0.388, p=0.004 at baseline; r=0.385, p=0.011 at follow-up) and inversely related to LVEF at both times (r=-0.484, p<0.001 at baseline; r=-0.461, p<0.001 at follow-up). Patients with adverse remodelling showed higher baseline copeptin values compared to patients without remodelling (p=0.02). Receiver operating characteristic analysis indicated a cut-off value of 16.7 pmol/l for copeptin to best identify patients with future adverse remodelling.

CONCLUSIONS

Increased copeptin values 2 days after STEMI are associated with larger acute and chronic infarct sizes. Moreover, elevated copeptin concentrations at baseline were associated with myocardial function and remodelling 4 months post-STEMI. These findings strengthen the role of copeptin as a biomarker of adverse outcome after STEMI.

Copeptin constitutes a novel biomarker of degenerative aortic stenosis

Copeptin is a new biomarker of cardiovascular diseases. Its diagnostic value in degenerative aortic valve stenosis (AS) with preserved left ventricle systolic function is unknown. We aimed to assess the association of serum copeptin levels with AS severity and coexistence of coronary artery disease (CAD). Sixty-four patients with AS and preserved left ventricle systolic function including 40 with severe degenerative AS (group sAS, effective orifice area EOA = 0.67 cm(2)) and 24 with moderate degenerative AS (group mAS, EOA = 1.40 cm(2)) were enrolled into the study. Twenty-three patients without AS and heart failure, matched for age, sex, and CAD occurrence served as the control group (group C). Serum levels of copeptin and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using enzyme-linked immunosorbent assay. The mean serum copeptin concentrations were significantly higher in patients with AS: sAS (405 pg/ml) and mAS (351 pg/ml; sAS vs mAS P < 0.05), compared with group C (302 pg/ml, P < 0.05). Serum copeptin levels correlated inversely with EOA (r = -0.55; P < 0.001) in AS patients. There was no correlation between copeptin and NT-proBNP or association with the coexisting CAD. Receiver-operating characteristics analysis showed that copeptin was a good marker of severe/moderate AS (sensitivity 71 %; specificity 87 %), with the optimized cut-off value of 354 pg/ml. Serum copeptin concentration constitutes a novel biomarker of degenerative AS. Coexisting CAD does not interfere with copeptin level.

Anti-depression effects of Danggui-Shaoyao-San, a fixed combination of Traditional Chinese Medicine, on depression model in mice and rats

Anti-depression effects of Danggui-Shaoyao-San (DSS, 1.8-7.2g/kg, orally), a famous Chinese compound prescription with a fixed combination, on forced swimming test (FST) and chronic unpredictable mild stress (CUMS) model were investigated. DSS (7.2g/kg, orally, 7 days) shortened immobility time in FST model and DSS (3.6 or 7.2g/kg, orally, 21 days) increased the open-field activities and the percentage of sugar preference in CUMS model. DSS (7.2g/kg, orally, 21 days) also decreased the content of arginine vasopressin (AVP) in the pituitary and the expression of AVP mRNA in hypothalamus compared with the stress control group. These results demonstrated for the first time DSS has anti-depression effect and it may be influencing the central AVP system.

Combined determination of highly sensitive troponin T and copeptin for early exclusion of acute myocardial infarction: first experience in an emergency department of a general hospital

BACKGROUND

The purpose of this observational study was to test the diagnostic performance of the Elecsys® troponin T high-sensitive system combined with copeptin measurement for early exclusion of acute myocardial infarction (MI) in clinical practice.

METHODS

Troponin T high-sensitive (diagnostic cutoff: <14 pg/mL) and copeptin (diagnostic cutoff: <14 pmol/L) levels were determined at admission in addition to other routine laboratory parameters in patients with suspected acute MI presenting to the emergency department of a general hospital over a period of five months.

RESULTS

Data from 142 consecutive patients (mean age 71.2 ± 13.5 years, 76 men) were analyzed. Final diagnoses were acute MI in 13 patients (nine ST elevation MI, four non-ST elevation MI, 9.2%) unstable angina pectoris in three (2.1%), cardiac symptoms not primarily associated with myocardial ischemia in 79 (55.6%), and noncardiac disease in 47 patients (33.1%). The patients with acute MI were younger and had higher troponin T high-sensitive and copeptin values than patients without acute MI. Seventeen patients had very high copeptin values (>150 pmol/L), one of whom had a level of >700 pmol/L and died of pulmonary embolism. A troponin T high-sensitive level of <14 pg/mL in combination with copeptin <14 pmol/L at initial presentation ruled out acute MI in 45 of the 142 patients (31.7%), each with a sensitivity and negative predictive value of 100%.

CONCLUSION

According to this early experience, a single determination of troponin T high-sensitive and copeptin may enable early and accurate exclusion of acute MI in one third of patients, even in an emergency department of a general hospital.

Copeptin: a biomarker of cardiovascular and renal function

Arginine vasopressin (AVP or antidiuretic hormone) is one of the key hormones in the human body responsible for a variety of cardiovascular and renal functions. It has so far escaped introduction into the routine clinical laboratory due to technical difficulties and preanalytical errors. Copeptin, the C-terminal part of the AVP precursor peptide, was found to be a stable and sensitive surrogate marker for AVP release. Copeptin behaves in a similar manner to mature AVP in the circulation, with respect to osmotic stimuli and hypotension. During the past years, copeptin measurement has been shown to be of interest in a variety of clinical indications, including cardiovascular diseases such as heart failure, myocardial infarction, and stroke. This review summarizes the recent progress on the diagnostic use of copeptin in cardiovascular and renal diseases and discusses the potential use of copeptin measurement in the context of therapeutic interventions with vasopressin receptor antagonists.

Hyponatremia and congestive heart failure: a marker of increased mortality and a target for therapy

Heart failure is one of the most common chronic medical conditions in the developed world. It is characterized by neurohormonal activation of multiple systems that can lead to clinical deterioration and significant morbidity and mortality. In this regard, hyponatremia is due to inappropriate and continued vasopressin activity despite hypoosmolality and volume overload. Hyponatremia is also due to diuretic use in an attempt to manage volume overload. When hyponatremia occurs, it is a marker of heart failure severity and identifies patients with increased mortality. The recent introduction of specific vasopressin-receptor antagonists offers a targeted pharmacological approach to these pathophysiological derangements. Thus far, clinical trials with vasopressin-receptor antagonists have demonstrated an increase in free-water excretion, improvement in serum sodium, modest improvements in dyspnea but no improvement in mortality. Continued clinical trials with these agents are needed to determine their specific role in the treatment of both chronic and decompensated heart failure.

Copeptin levels associate with cardiovascular events in patients with ESRD and type 2 diabetes mellitus

In ESRD, the neurohormone arginine vasopressin (AVP) may act primarily through V1a and V1b receptors, which promote vasoconstriction, myocardial hypertrophy, and release of adrenocorticotropic hormone. The preanalytical instability of AVP limits the investigation of whether this hormone associates with cardiovascular events, but the stable glycopeptide copeptin may serve as a surrogate because it is co-secreted with AVP from the posterior pituitary. Here, we studied whether copeptin predicts cardiovascular risk and mortality in ESRD. We measured copeptin at baseline in 1241 hemodialysis patients with type 2 diabetes participating in the German Diabetes and Dialysis Study. The median copeptin level was 81 pmol/L (interquartile range, 81 to 122 pmol/L). In Cox regression analyses, compared with patients with copeptin levels in the lowest quartile (≤51 pmol/L), patients with copeptin levels in the highest quartile (>122 pmol/L) had a 3.5-fold increased risk for stroke (HR, 3.48; 95% CI: 1.71 to 7.09), a 73% higher risk for sudden death (HR, 1.73; 95% CI: 1.01 to 2.95), a 42% higher risk for combined cardiovascular events (HR, 1.42; 95% CI: 1.06 to 1.90), and a 48% higher risk for all-cause mortality (HR, 1.48; 95% CI: 1.15 to 1.90). In contrast, we did not detect significant associations between copeptin levels and risks for myocardial infarction or death caused by congestive heart failure. In conclusion, copeptin levels strongly associate with stroke, sudden death, combined cardiovascular events, and mortality in hemodialysis patients with type 2 diabetes. Whether vasopressin receptor antagonists will improve these outcomes requires further studies.

Biomarkers in acute myocardial infarction

Myocardial infarction causes significant mortality and morbidity. Timely diagnosis allows clinicians to risk stratify their patients and select appropriate treatment. Biomarkers have been used to assist with timely diagnosis, while an increasing number of novel markers have been identified to predict outcome following an acute myocardial infarction or acute coronary syndrome. This may facilitate tailoring of appropriate therapy to high-risk patients. This review focuses on a variety of promising biomarkers which provide diagnostic and prognostic information. Heart-type Fatty Acid Binding Protein and copeptin in combination with cardiac troponin help diagnose myocardial infarction or acute coronary syndrome in the early hours following symptoms. An elevated N-Terminal Pro-B-type Natriuretic Peptide has been well validated to predict death and heart failure following a myocardial infarction. Similarly other biomarkers such as Mid-regional pro-Atrial Natriuretic Peptide, ST2, C-Terminal pro-endothelin 1, Mid-regional pro-Adrenomedullin and copeptin all provide incremental information in predicting death and heart failure. Growth differentiation factor-15 and high-sensitivity C-reactive protein predict death following an acute coronary syndrome. Pregnancy associated plasma protein A levels following chest pain predicts risk of myocardial infarction and revascularisation. Some biomarkers such as myeloperoxidase and high-sensitivity C-reactive protein in an apparently healthy population predicts risk of coronary disease and allows clinicians to initiate early preventative treatment. In addition to biomarkers, various well-validated scoring systems based on clinical characteristics are available to help clinicians predict mortality risk, such as the Thrombolysis In Myocardial Infarction score and Global Registry of Acute Coronary Events score. A multimarker approach incorporating biomarkers and clinical scores will increase the prognostic accuracy. However, it is important to note that only troponin has been used to direct therapeutic intervention and none of the new prognostic biomarkers have been tested and proven to alter outcome of therapeutic intervention. Novel biomarkers have improved prediction of outcome in acute myocardial infarction, but none have been demonstrated to alter the outcome of a particular therapy or management strategy. Randomised trials are urgently needed to address this translational gap before the use of novel biomarkers becomes common practice to facilitate tailored treatment following an acute coronary event.

Hyponatremia in heart failure: the role of arginine vasopressin and diuretics

PURPOSE

To provide an overview of the role of arginine vasopressin (AVP) in the development of hyponatremia in patients with heart failure (HF), the role of diuretics, and the potential for vasopressin-receptor antagonists in the treatment of HF.

METHODS

A MEDLINE literature search was performed to identify articles relating to HF, diuretics, hyponatremia, AVP, and vasopressin-receptor antagonists.

DISCUSSION

HF affects more than 5 million patients in the United States and is associated with substantial cost, morbidity, and mortality. One of the complications associated with HF, as well as with its treatment, is the development of hyponatremia. Hyponatremia in patients with HF is associated with poor outcomes and can limit the use of diuretic therapy. AVP is the primary stimulus to the development of hyponatremia in these patients and therapies that target AVP action would seem a logical choice in the therapeutic regimen for HF. Drugs that antagonize the vasopressin V(2) receptor, which is primarily responsible for water resorption in the kidney, are now available and have been studied in patients with HF. These drugs have been associated with improvements in serum sodium concentration, urine output, and body weight, but have shown no long-term mortality benefit in patients with HF. In a subset of patients with baseline hyponatremia, these agents improved quality of life scores.

CONCLUSION

Vasopressin-receptor antagonists may prove useful in the treatment of HF; however, the exact role of these agents in the treatment of HF still requires further study.

Chronic Cardiovascular Effects of Central Vasopressin in Conscious Rats

To clarify the cardiovascular effects of central vasopressin (AVP), a chronic intracerebroventricular (ICV) infusion of AVP was performed in conscious Wistar normotensive rats. Animals were divided into 3 groups: 1) AVP 1 ng/hr (Low), 2) AVP 100 ng/hr (High), and 3) saline (control) ICV infusion. After a 6 day control period, AVP or saline was continuously infused into the lateral cerebroventricle at a rate of 1 microliter/hr using osmotic minipump for 7 days. As a result, a dose-related elevation of AVP concentration in CSF was achieved. Systolic blood pressure in both Low and High AVP infusion was slightly (7-12 mmHg) but significantly higher than that in control. ICV infusion of AVP did not alter urine volume, electrolytes excretion or osmolality, and AVP vascular antagonist injected intravenously failed to affect mean arterial pressure. Furthermore, plasma catecholamines and renin activity did not differ significantly among the groups. Thus, chronic ICV infusion of AVP induced the elevation of blood pressure, which is due to centrally mediated effect of AVP.

C-terminal provasopressin (copeptin) is associated with left ventricular dysfunction, remodeling, and clinical heart failure in survivors of myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is associated with left ventricular (LV) dysfunction and clinical heart failure. Arginine vasopressin is elevated in heart failure and the C-terminal of provasopressin (Copeptin) is associated with adverse outcome post-AMI. The aim of this study was to describe the association between Copeptin with LV dysfunction, volumes, and remodeling and clinical heart failure post-AMI.

METHODS AND RESULTS

We studied 274 subjects with AMI. Copeptin was measured from plasma at discharge and subjects underwent echocardiography at discharge and follow-up (median 155 days). Subjects were followed for clinical heart failure for a median of 381 days. Remodeling was assessed as the change (Delta) in LV volumes between echo examinations. Copeptin correlated directly with wall motion index score (WMIS) and inversely with LV ejection fraction (LVEF) at discharge (WMIS, r=0.276, P < .001; LVEF, r=-0.188, P=.03) and follow-up (WMIS, r=0.244, P < .001; LVEF, r=-0.270, P < .001) and with ventricular volumes at follow-up (LVEDV, r=0.215, P=.002; LVESV, r=0.299, P < .001). Copeptin was associated with ventricular remodeling; DeltaEDV; r=0.171, P=0.015, DeltaESV; r=0.186, P=.008. Subjects with increasing LVESV had higher levels of Copeptin (median 6.30 vs. 5.75 pmol/L, P=.012). Subjects with clinical heart failure (n=30) during follow-up had higher Copeptin before discharge (median 13.55 vs. 5.80, P < .001). In a Cox proportional hazards model, Copeptin retained association with clinical heart failure. Kaplan-Meier assessment revealed increased risk in subjects with Copeptin >6.31 pmol/L.

CONCLUSIONS

Copeptin is associated with LV dysfunction, volumes, and remodeling and clinical heart failure post-AMI. Measurement of Copeptin may provide prognostic information and the AVP system may be a therapeutic target in post-MI LV dysfunction.

C-terminal provasopressin (copeptin) as a novel and prognostic marker in acute myocardial infarction: Leicester Acute Myocardial Infarction Peptide (LAMP) study

BACKGROUND

The role of the vasopressin system after acute myocardial infarction is unclear. Copeptin, the C-terminal part of the vasopressin prohormone, is secreted stoichiometrically with vasopressin. We compared the prognostic value of copeptin and an established marker, N-terminal pro-B-type natriuretic peptide (NTproBNP), after acute myocardial infarction.

METHODS AND RESULTS

In this prospective single-hospital study, we recruited 980 consecutive post-acute myocardial infarction patients (718 men, median [range] age 66 [24 to 95] years), with follow-up over 342 (range 0 to 764) days. Plasma copeptin was highest on admission (n=132, P<0.001, day 1 versus days 2 to 5) and reached a plateau at days 3 to 5. In the 980 patients, copeptin (measured at days 3 to 5) was elevated in patients who died (n=101) or were readmitted with heart failure (n=49) compared with survivors (median [range] 18.5 [0.6 to 441.0] versus 6.5 [0.3 to 267.0] pmol/L, P<0.0005). With logistic regression analysis, copeptin (odds ratio, 4.14, P<0.0005) and NTproBNP (odds ratio, 2.26, P<0.003) were significant independent predictors of death or heart failure at 60 days. The area under the receiver operating characteristic curves for copeptin (0.75) and NTproBNP (0.76) were similar. The logistic model with both markers yielded a larger area under the curve (0.84) than for NTproBNP (P<0.013) or copeptin (P<0.003) alone, respectively. Cox modeling predicted death or heart failure with both biomarkers (log copeptin [hazard ratio, 2.33], log NTproBNP [hazard ratio, 2.70]). In patients stratified by NTproBNP (above the median of approximately 900 pmol/L), copeptin above the median (approximately 7 pmol/L) was associated with poorer outcome (P<0.0005). Findings were similar for death and heart failure as individual end points.

CONCLUSIONS

The vasopressin system is activated after acute myocardial infarction. Copeptin may predict adverse outcome, especially in those with an elevated NTproBNP (more than approximately 900 pmol/L).

Copeptin, a fragment of the vasopressin precursor, as a novel predictor of outcome in heart failure

BACKGROUND

Natriuretic peptides, particularly brain natriuretic peptide (BNP), are elevated in heart failure and therefore considered to be excellent predictors of outcome. Vasopressin is also known to be related to the severity of heart disease. Copeptin--an inactive fragment of the vasopressin precursor--has not been previously investigated in the context of heart failure.

MATERIALS AND METHODS

We prospectively studied 268 patients with advanced heart failure after they had been discharged from the hospital. We investigated the ability of BNP and copeptin to predict death, re-hospitalization due to heart failure, and a combination of the two endpoints.

RESULTS

Over a mean follow-up period of 15.8 months (up to 24 months), 83 patients died, 122 patients experienced worsening of heart failure, and 145 patients achieved the combined endpoint. Univariate predictors of death were copeptin, BNP, age and impaired kidney function. In multivariate analysis, copeptin (chi(2) = 16, P < 0.0001) and age (chi(2) = 4, P < 0.05) were independent predictors. Univariate predictors of re-hospitalization due to heart failure were copeptin, BNP, age and impaired kidney function. Furthermore, in multivariate analysis BNP (chi(2) = 18, P < 0.0001), age (chi(2) = 11.8, P < 0.001) and copeptin (chi(2) = 4.2, P < 0.05) were found to be independent predictors.

CONCLUSION

Our study is the first to show that copeptin is an excellent predictor of outcome in advanced heart failure patients. Its value is superior to that of BNP in predicting death and a combined endpoint, although BNP is still suitable for predicting chronic heart failure (CHF) re-hospitalization. Our data imply that vasopressin antagonism might be a new target to improve outcome in this population.

Development and therapeutic indications of orally-active non-peptide vasopressin receptor antagonists

Vasopressin (AVP) and oxytocin (OT) are cyclic nonapeptides whose actions are mediated by the stimulation of specific G-protein-coupled receptors (GPCRs) currently classified into V(1)-vascular (V(1)R), V(2)-renal (V(2)R) and V(3)-pituitary (V(3)R) AVP receptors and OT receptors (OTR). The signal transduction pathways coupled to the different subtypes of AVP/OT receptors are reviewed. The recent cloning of the different members of the AVP/OT family of receptors now allows the extensive characterisation of the molecular determinants involved in agonist and antagonist binding, as well as signal transduction coupling. Potential therapeutic uses of AVP receptor antagonists include: the blockade of V(1)-vascular AVP receptors in arterial hypertension, congestive heart failure (CHF) and peripheral vascular diseases; the blockade of V(2)-renal AVP receptors in the syndrome of inappropriate vasopressin secretion, CHF, liver cirrhosis, nephrotic syndrome and any state of excessive retention of free water and subsequent hyponatraemia; the blockade of V(3)-pituitary AVP receptors in adrenocorticotropin (ACTH)-secreting tumours. The pharmacological and clinical profile of orally-active non-peptide AVP receptor antagonists is reviewed.

Vasopressin receptor antagonists in the management of acute heart failure

Vasopressin is a potent vasoconstrictor and plays a significant role in the regulation of volume homeostasis. Several non-peptide vasopressin receptor antagonists (vaptans) have emerged as promising drugs in the management of acute heart failure. Results of early trials with tolvaptan (selective vasopressin subtype 2 receptor antagonist) and conivaptan (dual vasopressin subtypes 1a and 2 receptor antagonist) have demonstrated improvement in the fluid status, osmotic balance and haemodynamic profile in patients with heart failure presenting with signs and symptoms of decompensation. Nevertheless, their comparative long-term safety and efficacy remains to be determined in large-scale clinical trials.

Use of vasopressors in the treatment of cardiac arrest

Intervention for cardiac arrest may require intervention for electrical abnormalities or hemodynamic instability. These actions can result in ineffective cardiac functioning and systemic hypotension. Vasopressors are capable of improving severe hypotension that can result from reduced cardiovascular contractility or heart rate. These vasopressor actions are critical to successful resuscitation efforts for patients.

Die Behandlung des hämorrhagischen Schocks

The future of shock treatment depends on the importance of scientific results, and the willingness of physicians to optimize, and to reconsider established treatment protocols. There are four major potentially promising approaches to advanced trauma life support. First, control of hemorrhage by administration of local hemostatic agents, and a better, target-controlled management of the coagulation system. Second, improving intravascular volume by recruiting blood from the venous vasculature by preventing mistakes during mechanical ventilation, and by employing alternative spontaneous (i.e. use of the inspiratory threshold valve) or artificial ventilation strategies. In addition, artificial oxygen carriers may improve intravascular volume and oxygen delivery. Third, pharmacologic support of physiologic, endogenous mechanisms involved in the compensation phase of shock, and blockade of pathomechanisms that are known to cause irreversible vasoplegia (arginine vasopressin and K(ATP) channel blockers for hemodynamic stabilization). Fourth, employing potentially protective strategies such as mild or moderate hypothermia. Finally, the ultimate vision of trauma resuscitation is the concept of "suspended animation" as a form of delayed resuscitation after protection of vital organ systems.

Terlipressin-Related Acute Myocardial Infarction: A Case Report and Literature Review

Acute ST-segment elevation myocardial infarction after the administration of terlipressin in patients with hemorrhagic esophageal varices is a rare but life-threatening complication. We report the case of a 73-year-old female patient with esophageal variceal bleeding complicated with acute ST-segment elevation myocardial infarction after intravenous injection of terlipressin. We discuss the underlying mechanisms of terlipressin-related acute myocardial infarction and review the literature.

Inhibitory effects of SR 49059 on oxytocin-and vasopressin-induced uterine contractions in non-pregnant women

BACKGROUND

Compounds that block uterine oxytocin and vasopressin V1a receptors have a therapeutic potential in preterm labor and primary dysmenorrhoea. The orally active vasopressin V1a receptor antagonist, SR49059, inhibits the effect of vasopressin on human uterine activity in vivo, but the influence on the response to oxytocin is unknown.

METHODS

In a placebo-controlled, double-blind, parallel-group, four-dose comparison, the inhibitory effect of SR 49059 on oxytocin- and vasopressin-induced uterine contractions in humans was investigated. Sixteen healthy female subjects, who had previously undergone sterilization with tubal ligation, participated in intrauterine pressure recordings at one of the first 3 days of bleeding of two menstrual cycles. Intravenous bolus injections of 10 pmol/kg body weight of vasopressin (Period 1) and of 50 pmol/kg body weight of oxytocin (Period 2) were given 1 h before and 1, 2 and 4 h after oral administration of 0 (placebo), 25, 75 or 200 mg of SR 49059. The area between the recording curve and zero level of intrauterine pressure (AUC) was calculated. Vital signs as well as urine and plasma safety parameters were measured. The plasma concentrations of oxytocin, vasopressin and the study drug were also estimated.

RESULTS

The plasma concentrations of SR 49059 appeared to be dose related, with mean maximal values of 62.0, 163.7 and 468.0 ng/ml in the 25, 75 and 200 mg dose groups, respectively, in Period 1 with vasopressin and 34.4, 116.7 and 418.0 ng/mL, respectively, in Period 2 with oxytocin. Tmax was observed at about 1 h. The cumulative AUC over 50 min after vasopressin injection per se was significantly higher than that after oxytocin in spite of a five times lower dose and lower plasma concentrations. Pretreatment by SR 49059 caused a dose-related reduction in AUCs for vasopressin, whereas no such effect was seen for oxytocin. With vasopressin as an agonist, a lower diastolic blood pressure was observed in all SR 49059 treatment groups, but not with oxytocin.

CONCLUSIONS

The much higher potency of vasopressin compared with oxytocin on uterine activity in non-pregnant women at menstruation was confirmed. SR 49059 dose-dependently inhibits vasopressin-induced contractions, whereas such an effect was not seen with the present doses of SR 49059 and oxytocin. A marked reduction by SR 49059 of diastolic blood pressure after vasopressin injection was observed, indicating an inhibition by this compound of vascular vasopressin receptors.

Identification of the binding sites of the SR49059 nonpeptide antagonist into the V1a vasopressin receptor using sulfydryl-reactive ligands and cysteine mutants as chemical sensors

To identify the binding site of the human V1a vasopressin receptor for the selective nonpeptide antagonist SR49059, we have developed a site-directed irreversible labeling strategy that combines mutagenesis of the receptor and use of sulfydryl-reactive ligands. Based on a three-dimensional model of the antagonist docked into the receptor, hypothetical ligand-receptor interactions were investigated by replacing the residues potentially involved in the binding of the antagonist into cysteines and designing analogues of SR49059 derivatized with isothiocyanate or alpha-chloroacetamide moieties. The F225C, F308C, and K128C mutants of the V1a receptor were expressed in COS-7 or Chinese hamster ovary cells, and their pharmacological properties toward SR49059 and its sulfydryl-reactive analogues were analyzed. We demonstrated that treatment of the F225C mutant with the isothiocyanate-derivative compound led to dose-dependent inhibition of the residual binding of the radio-labeled antagonist [125I]HO-LVA. This inhibition is probably the consequence of a covalent irreversible chemical modification, which is only possible when close contacts and optimal orientations exist between reactive groups created both on the ligand and the receptor. This result validated the three-dimensional model hypothesis. Thus, we propose that residue Phe225, located in transmembrane domain V, directly participates in the binding of the V1a-selective nonpeptide antagonist SR49059. This conclusion is in complete agreement with all our previous data on the definition of the agonist/antagonist binding to members of the oxytocin/vasopressin receptor family.

Vasopressin: a new target for the treatment of heart failure

BACKGROUND

Arginine vasopressin is a peptide hormone that modulates a number of processes implicated in the pathogenesis of heart failure. Numerous vasopressin antagonists are currently under development for the treatment of this syndrome.

METHODS

Preclinical and clinical data describing the effects of vasopressin and the vasopressin antagonists on both normal physiology and heart failure were reviewed.

RESULTS

Through activation of V(1a) and V(2) receptors, vasopressin regulates various physiological processes including body fluid regulation, vascular tone regulation, and cardiovascular contractility. Vasopressin synthesis is significantly and chronically elevated in patients with heart failure despite the volume overload and reductions in plasma osmolality often observed in these patients. Vasopressin also appears to adversely effect hemodynamics and cardiac remodeling, while potentiating the effects of norepinephrine and angiotensin II. The selective V(2) and dual V(1a)/V(2) receptor antagonists tolvaptan and conivaptan, respectively, substantially increase free water excretion and plasma osmolality, reduce body weight, improve symptoms of congestion, and moderately increase serum sodium concentrations in patients with heart failure who present with symptoms of fluid overload. Tolvaptan effectively normalizes serum sodium concentrations in hyponatremic heart failure patients. Conivaptan significantly reduces pulmonary capillary wedge pressure without affecting systemic vascular resistance or cardiac output. The clinical significance of V(1a) receptor antagonism requires further investigation.

CONCLUSIONS

Current preclinical and clinical findings with the vasopressin antagonists appear promising, however further evaluation in phase III clinical trials is necessary to define the role of vasopressin antagonism in the treatment of heart failure.

Pharmacologic options available to treat symptomatic intradialytic hypotension

Treatment of symptomatic intradialytic hypotension (IDH) is a difficult task for the practicing nephrologist. Minimizing patient factors that precipitate IDH as well as dialysis procedure-related components that lower blood pressure are the initial approaches to this problem. However, despite these maneuvers, hypotension often persists in a group of high-risk patients. Pharmacologic interventions are often used to reduce IDH. Unfortunately, many of the available therapies are marginally effective and/or poorly tolerated. A few therapies appear to be efficacious and well tolerated-carnitine, sertraline, and midodrine. This article reviews the various pharmacologic therapies used for IDH and makes recommendations for treatment of this difficult problem.

The basic and clinical pharmacology of nonpeptide vasopressin receptor antagonists

The neurohypophysial hormone arginine vasopressin (AVP) is a cyclic nonpeptide whose actions are mediated by the stimulation of specific G protein--coupled membrane receptors pharmacologically classified into V1-vascular (V1R), V2-renal (V2R) and V3-pituitary (V3R) AVP receptor subtypes. The random screening of chemical compounds and optimization of lead compounds recently resulted in the development of orally active nonpeptide AVP receptor antagonists. Potential therapeutic uses of AVP receptor antagonists include (a) the blockade of V1-vascular AVP receptors in arterial hypertension, congestive heart failure, and peripheral vascular disease; (b) the blockade of V2-renal AVP receptors in the syndrome of inappropriate vasopressin secretion, congestive heart failure, liver cirrhosis, nephrotic syndrome and any state of excessive retention of free water and subsequent dilutional hyponatremia; (c) the blockade of V3-pituitary AVP receptors in adrenocorticotropin-secreting tumors. The pharmacological and clinical profile of orally active nonpeptide vasopressin receptor antagonists is reviewed here.

Study of V(1)-vascular vasopressin receptor gene microsatellite polymorphisms in human essential hypertension

Vasopressin (AVP) actions on vascular tone and blood pressure are mainly mediated by the V(1)-vascular receptor (V(1)R). We recently reported the structure and functional expression of the human V(1)R cDNA and described the genomic characteristics, tissue expression, chromosomal localization, and regional mapping of the human V(1)R gene, AVPR1A. To test whether the V(1)R is a marker for human essential hypertension, we sequenced the human AVPR1A gene and its 5; upstream region and found several DNA microsatellite motifs. One (GT)(14)-(GA)(13)-(A)(8)microsatellite is located 2983 bp downstream of the transcription start site, within a 2.2 kbp intron interrupting the coding sequence of the receptor. Three other microsatellites are present in the 5; flanking DNA of the AVPR1A gene: a (GT)(25)dinucleotide repeat, a complex (CT)(4)-TT-(CT)(8)-(GT)(24)motif and a (GATA)(14)tetranucleotide repeat located respectively 3956 bp, 3625 bp and 553 bp upstream of the transcription start site. Analysis of these polymorphisms in 79 hypertensive and 86 normotensive subjects for the (GT)(14)-(GA)(13)-(A)(8)and the (GT)(25)motifs revealed a high percentage of heterozygosity but no difference in alleles frequencies between the two groups. A linkage study using the affected sib pair method and the (GT)(25)repeat in 446 hypertensive sib pairs from 282 French Caucasian pedigrees showed no excess of alleles sharing at the AVPR1A locus. No linkage was found in the subgroups of patients with early onset hypertension (diagnosis before age 40) or severe hypertension (diastolic blood pressure >/=100 mmHg or requirement for >/=two medications). These findings suggest that molecular variants of the V(1)R gene are not involved in unselected forms of essential hypertension.

Effects of the nonpeptide V(1) vasopressin receptor antagonist SR49059 in hypertensive patients

We assessed the clinical and pharmacological profile of the orally active V(1) vascular vasopressin (AVP) receptor nonpeptide antagonist SR49059 (SR) during the osmotic stimulation of AVP release in hypertensive patients. In a double-blind crossover-versus-placebo study, 24 untreated stage I or II essential hypertensive patients (12 whites and 12 blacks) received a single 300 mg oral dose of SR 2 hours before the stimulation of AVP secretion with a 5% hypertonic saline infusion. Hemodynamic, humoral, and hormonal parameters were monitored for up to 28 hours after drug administration. SR did not alter blood pressure or heart rate before the saline infusion and did not reduce the blood pressure increment induced by the hypertonic saline infusion. However, the blood pressure peak at the end of the hypertonic saline infusion was slightly lower in the presence of SR (P=0.04). Heart rate was significantly faster between 4 and 6 hours after SR administration (P=0.02). The rise in plasma sodium and osmolality triggered by the saline infusion was not modified by SR, but AVP release was slightly greater in the presence of SR (P<0.0003). AVP-induced aggregation of blood platelets in vitro was significantly reduced by SR, with a peak effect 2 hours after drug administration that coincided with the SR peak plasma concentration. Plasma renin activity and aldosterone before and after the saline infusion were not modified by SR. Urine volume and osmolality were not altered by SR administration. SR effects were similar in the 2 ethnic groups as well as in salt-sensitive versus salt-resistant patients. In a situation of AVP osmotic release and volume expansion in hypertensive patients, a single oral dose of the V(1) vascular AVP receptor nonpeptide antagonist SR49059, which is able to block AVP-induced platelet aggregation, exerts a transient vasodilation effect that is not associated with a sustained blood pressure reduction. SR49059 is a pure V(1) vascular receptor antagonist that is devoid of V(2) renal receptor actions.