Exogenous Arginine Vasopressin Research Articles

Effects of arginine vasopressin on human anxiety and associations with sex, dose, and V1a-receptor genotype.

Arginine vasopressin (AVP) has dose- and sex-specific effects on social behavior, and variation in social responses is related to variation in the V1a receptor gene in animals. Whether such complexity also characterizes AVP effects on anxiety in humans, or whether V1a genotype is related to anxiety and/or AVP's ability to affect it, remains to be determined. To test if AVP has dose-dependent effects on anxiety in men and/or women and if a particular allele within the RS3 promoter region of the V1a receptor gene is associated with anxiety and/or AVP effects on anxiety. Men and women self-administered 20IU or 40IU intranasal arginine vasopressin (AVP) and placebo in a double-blind, within-subjects design, and State (SA) and Trait (TA) anxiety were measured 60min later. PCR was used to identify allelic variation within the RS3 region of the V1a receptor gene. AVP decreased SA in men across both doses, whereas only the lower dose had the same effect, across sexes, in individuals who carry at least one copy of a previously identified "risk" allele in the RS3 promoter of the V1a receptor gene. Additionally, after placebo, women who carried a copy of the allele displayed lower TA than women who did not, and AVP acutely increased TA scores in those women. Exogenous AVP has modest sex- and dose-dependent effects on anxiety/affect in humans. Further, allelic variation in the V1a promoter appears associated with responsiveness to AVP's effects and, at least in women, to stable levels of anxiety/affect.

Vasopressin acts as a synapse organizer in limbic regions by boosting PSD95 and GluA1 expression.

Hypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behaviour, and fear responses. Here, we characterize the dynamics of expression changes of two key determinants for synaptic strength, the postsynaptic density (PSD) proteins AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), in response to in vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP ex vivo. Both long-term water deprivation in vivo, which powerfully upregulates AVPMNN metabolic activity, and exogenous AVP application ex vivo, in brain slices, significantly increased GluA1 and PSD95 expression as measured by western blotting, in brain regions reportedly receiving direct ascending innervations from AVPMNN (i.e., ventral hippocampus, amygdala and lateral habenula). By contrast, the visual cortex, a region not observed to receive AVPMNN projections, showed no such changes. Ex vivo application of V1a and V1b antagonists to ventral hippocampal slices ablated the AVP stimulated increase in postsynaptic protein expression measured by western blotting. Using a modified expansion microscopy technique, we were able to quantitatively assess the significant augmentation of PSD95 and GLUA1 densities in subcellular compartments in locus coeruleus tyrosine hydroxylase immunopositive fibres, adjacent to AVP axon terminals. Our data strongly suggest that the AVPMNN ascending system plays a role in the regulation of the excitability of targeted neuronal circuits through upregulation of key postsynaptic density proteins corresponding to excitatory synapses.

Arginine vasopressin attenuates the effects of TNF-α in aortic endothelial cells by inducing ectodomain shedding of TNF receptor 1

In septic shock, arginine vasopressin (AVP) is commonly used as a vasopressor to restore blood pressure. Exogenous AVP may have anti-inflammatory effects as well. We investigated whether AVP modulates the effects of tumor necrosis factor-α (TNF-α) in human aortic endothelial cells (HAECs). TNF-α stimulated intercellular adhesion molecule-1 expression, while AVP pretreatment attenuated this effect of TNF-α. Upon treatment with AVP, extracellular Ca2+ entered the cells rapidly through L-type calcium channels, which in turn induced cell surface translocation of a disintegrin and metalloprotease 10 (ADAM10) and ectodomain shedding of tumor necrosis factor receptor 1 (TNFR1). On the other hand, siRNA depletion of ADAM10 suppressed AVP-induced ectodomain shedding of TNFR1 and eliminated the inhibitory effect of AVP against TNF-α. Depletion of oxytocin receptor also abolished AVP-induced extracellular Ca2+ influx, AVP-induced ectodomain shedding of TNFR1 and the inhibitory effect of AVP against TNF-α. These findings suggest that AVP decreases the responsiveness of HAECs to TNF-α by inducing ADAM10-dependent ectodomain shedding of TNFR1. Extracellular Ca2+ influx through L-type calcium channels was essential for ADAM10 activation. This effect of AVP was mediated through the oxytocin receptor.

Adenine acts in the kidney as a signaling factor and causes salt- and water-losing nephropathy: early mechanism of adenine-induced renal injury.

Chronic adenine feeding is extensively used to develop animal models of chronic renal failure with metabolic features resembling those observed in humans. However, the mechanism by which adenine induces renal failure is poorly understood. In this study, we examined the early effects of adenine on water metabolism and salt balance in rats placed in metabolic cages and fed control or adenine-containing diets for 7 days. Molecular and functional studies demonstrated that adenine-fed rats exhibited a significant reduction in food intake, polyuria, polydipsia, decreased urine osmolality, and increased salt wasting. These effects are independent of changes in food intake and result from a coordinated downregulation of water channel aquaporin-2 (AQP2) and salt transporter (Na+-K+-Cl- cotransporter 2; NKCC2) in the collecting duct and medullary thick ascending limb, respectively. As a result, adenine-fed rats exhibited massive volume depletion, as indicated by a significant body weight loss, increased blood urea nitrogen, and increased hematocrit and hemoglobin levels, all of which were significantly corrected with NaCl replacement. Adenine-induced urinary concentrating defect was not corrected by exogenous arginine vasopressin (AVP), and it correlated with reduced cAMP production in vivo and in vitro. In conclusion, adenine acts on renal tubules as a signaling molecule and causes nephrogenic diabetes insipidus with salt wasting, at least, by directly interfering with AVP V2 receptor signaling with subsequent downregulation of NKCC2 and AQP2 in the kidney. The combination of renal fluid loss and decreased food intake with subsequent massive volume depletion likely plays an important role in the development of early prerenal failure that progresses to chronic kidney disease in long-term adenine feeding.

Vasopressin therapy in cardiac surgery.

Arginine vasopressin (AVP) is a naturally occurring peptide with diverse effects mediated through selective V1 and V2 receptors. About 10% of patients undergoing cardiopulmonary bypass develop postoperative vasodilatory shock requiring high-dose catecholamines. We sought to examine the role of AVP therapy in cardiac surgery. A search of Medline was conducted through September 2018 using key words and medical subject headings (MeSH) relating to AVP, copeptin, and cardiac surgery. A systematic review was performed on articles as they pertained to AVP for use as a vasopressor after cardiovascular surgery complicated by vasodilatory shock. A relative or absolute deficiency of Arginine vasopressin is associated with vasodilatory shock after cardiopulmonary bypass. Physiologic replacement with exogenous Arginine vasopressin results in significant increases in systemic vascular resistance and mean arterial pressure with decreased requirements of catecholamines. At doses of <0.1 U/min Arginine vasopressin is safe with very few adverse effects. Post-cardiopulmonary bypass vasodilatory shock is largely due to a relative deficiency of Arginine vasopressin. Exogenous administration of low-dose Arginine vasopressin alone or in combination with traditional catecholamines is a safe and effective way to manage this type of vasodilatory shock.

Supplemental arginine vasopressin during the resuscitation of severe hemorrhagic shock preserves renal mitochondrial function

Arginine vasopressin (AVP), a hormone secreted by the posterior pituitary, plays a vital role in maintaining vasomotor tone during acute blood loss. We hypothesized that decompensated hemorrhagic shock is associated with decreased AVP stores and supplementation during resuscitation would improve both blood pressure and renal function. Using a decompensated hemorrhagic shock model, male Long-Evans rats were bled to mean arterial blood pressure (MAP) of 40mmHg and maintained until the MAP could not be sustained without fluid. Once 40% of the shed volume was returned in lactated Ringer’s (Severe Shock), animals were resuscitated over 60 minutes with 4x the shed volume in lactated Ringer’s (LR) or the same fluids with AVP (0.5 units/kg+ 0.03 units/kg/min). Animals (n = 6-9/group) were sacrificed before hemorrhage (Sham), at Severe Shock, following resuscitation (60R, 60R with AVP) or 18 hours post-resuscitation (18hr, 18hr with AVP). Blood samples were taken to measure AVP levels and renal function. Pituitaries were harvested and assayed for AVP. Kidney samples were taken to assess mitochondrial function, histology, and oxidative damage. Baseline pituitary AVP stores (30,364 ± 5311 pg/mg) decreased with severe shock and were significantly depressed post-resuscitation (13,910 ± 3016 pg/ml. p<0.05) and at 18hr (15,592 ±1169 pg/ml, p<0.05). Resuscitation with LR+AVP led to higher serum AVP levels at 60R (31±8 vs 79±12; p<0.01) with an improved MAP both at 60R (125±3 vs 77±7mmHg; p<0.01) and 18hr (82±6 vs 69±5mmHg;p<0.05). AVP supplementation preserved complex I respiratory capacity at 60R and both complex I and II function at 18hr (p<0.05). AVP was also associated with decreased reactive oxygen species at 60R (856±67 vs 622±48F RFU) and significantly decreased oxidative damage as measured by mitochondrial lipid peroxidation (0.9±0.1 vs 1.7±0.1 fold change, p<0.01) and nitrosylation (0.9±0.1 vs 1.4±0.2 fold change, p<0.05). With AVP, renal damage was mitigated at 60R and histologic architecture was conserved at 18 hours. In conclusion, pituitary and serum AVP levels decrease during severe hemorrhage and may contribute to the development of decompensated hemorrhagic shock. Supplementing exogenous AVP during resuscitation improves blood pressure, preserves renal mitochondrial function, and mitigates acute kidney injury.

Regulation of Pulsatile and Entropic ACTH Secretion Under Fixed Exogenous Secretagogue Clamps.

Adrenocorticotropic hormone (ACTH) secretion is controlled by unobservable hypothalamic corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) pulses. Clamping exogenous CRH or AVP input could allow indirect quantification of the impact of the endogenous heterotypic hormone. We conducted a randomized, double-blind, placebo-controlled, crossover study in 28 healthy adults (16 men). Volunteers underwent a sex-steroid clamp and a cortisol clamp. ACTH was measured over 10 hours by 10-minute sampling during each of four randomized intravenous (IV) secretagogue clamps (i.e., continuous IV CRH, AVP, both peptides, or saline). Desensitization was tested by bolus injection of the noninfused peptide. Mean ± standard error of the mean 10-hour ACTH concentrations (ng/L) in the sex-combined analysis were: saline, 32 ± 4.6; AVP, 29 ± 4.6; CRH, 67 ± 6.2; and CRH-AVP, 67 ± 8.8 (any CRH vs AVP or saline, P < 0.0001). CRH and AVP increased approximate entropy (relative randomness) of ACTH release (P < 0.0001). Bolus AVP injection after CRH infusion yielded a 2.5-hour ACTH concentration of 46 ± 4.3, exceeding that seen after bolus CRH or saline injection (26 ± 3.3 and 24 ± 3.6, respectively; P = 0.002 and 0.001). Sex hormone clamps did not influence ACTH levels. A CRH, but not AVP, clamp yields sustained pulsatile ACTH secretion with high ACTH secretory-burst mass and randomness. After 10-hour CRH infusion, bolus AVP but not CRH, evoked marked ACTH release, likely caused by heterotypic sensitization of corticotropes by CRH. Similar interactions might underlie chronic stress states.

Rationale for early treatment of polycystic kidney disease.

In hereditary cystic disorders, renal injury begins with the formation of the first cyst. Renal injury may manifest as large kidneys, abdominal pain, hypertension and hematuria in children and young adults with autosomal dominant polycystic kidney disease (ADPKD). In autosomal recessive PKD (ARPKD) and ADPKD, cysts form primarily in collecting ducts and expand progressively. Collecting duct cysts that block urine flow have the potential to block urine formation in large numbers of upstream nephrons. In an ARPKD rat congenitally lacking vasopressin, only a few cysts developed until exogenous arginine vasopressin (AVP) was administered. AVP elevates cyclic AMP in vulnerable tubule cells to stimulate mitogenesis and fluid secretion, thereby causing cysts to form and enlarge indefinitely. The administration of an AVP-V2 receptor inhibitor or the consumption of sufficient water to persistently lower plasma AVP levels will ameliorate disease progression. Renal volume measurements provide the most reliable way to forecast long-term outcome in individual children and adult patients with ADPKD. Many drugs that have demonstrated efficacy in small clinical trials, preclinical trials and cell-based studies are in the treatment pipeline. Counseling, regular exercise, limitation of dietary calories, salt, protein and fat, increased fluid intake throughout the day and treatment of hypertension are components of a rational treatment program that can be offered at an early age to those with, or at risk for developing PKD.

A novel deletion mutation of the arginine vasopressin receptor 2 gene in a Japanese infant with nephrogenic diabetes insipidus.

Arginine vasopressin (AVP) is released from the posterior pituitary. It controls water balance homeostasis. It binds to arginine vasopressin receptor 2 (AVPR2) on the basolateral membrane of the kidney collecting duct and triggers activation of Gs proteins, which leads to increases in intracellular cAMP and the activity of protein kinase A. These increases cause trafficking of aquaporin-2 (AQP2) water channels to the apical membrane of collecting duct cells, resulting in increased water permeability and antidiuresis. The AVPR2 gene encodes a 7-transmembrane-spanning G protein-coupled receptor, which is located on chromosome Xq28. AVPR2 mutations, which are typically loss-of-function mutations, explain approximately 90% of cases of hereditary nephrogenic diabetes insipidus (NDI) (OMIM 304800). NDI is characterized by an inability to concentrate urine, resulting in excessive urine production, dehydration and thirst. Administration of exogenous AVP cannot restore the normal balance of water in most patients with AVPR2 mutations. We describe a Japanese infant with NDI who has a novel deletion mutation of the AVPR2 gene.

Abstract 18566: V1A Receptor Overexpression in the Murine Heart Depresses the Inotropic Response to Catecholamines

Background: — Circulating levels of arginine vasopressin (AVP), a vasoconstrictor, are elevated in patients with heart failure. In the heart, AVP induces effects through the V1A receptor. The goal of this study was to better define the role of AVP in cardiac contractile dysfunction in the diseased heart. We utilized an inducible, cardiac-specific V1A receptor overexpression (V1A-OE) mouse model to explore the effects of AVP signaling in cardiac myocytes. Methods and Results: — Isolated WT and V1A-OE hearts were studied using a Langendorff apparatus. A fluid-filled balloon was inserted into the LV to record isovolumic ventricular pressure. Each heart underwent a 20min equilibration period, followed by administration of ISO or IBMX for 3min each. ISO [10 -5 ] had significantly smaller inotropic effects in V1A-OE (n=8) compared to WT hearts (n=5) (LVDP% V1A-TG: 129±14.04% increase vs. WT: 191.5±20.80%). WT hearts (n=4) pretreated with exogenous AVP [10 -9 ] also had significantly smaller inotropic responses to ISO [10 -5 ] (LVDP% WT+AVP: 118.8±12.30). The phosphodiesterase inhibitor IBMX [10 -5 ] had enhanced contractility in WT (n=5) significantly more than in V1A-OE (n=5) (LVDP% V1A-OE: 99.40±6.61 vs. WT 149.4±8.135). Western blot analysis showed reduced levels of phospholamban (PLB) phosphorylation at Serine-16, a PKA phosphorylation site, in the V1A-OE+IBMX compared to WT+IBMX. Conclusions: — These results suggest that V1A overexpression reduces myocardial inotropic regulation by inhibiting PKA-induced phosphorylation of Ca 2+ regulatory proteins that are involved in β-adrenergic regulation of cardiac contractility. Increased AVP signaling plays a role in the depression of cardiac contractility in heart failure and AVP antagonists may improve heart function by enhancing cardiac contractility reserve.

EComment. Potential therapeutic agents in vasoplegic syndrome after cardiac surgery

Vasoplegic syndrome (VS) or vasodilatory shock frequently occurs after cardiac surgery, particularly with cardiopulmonary bypass(CPB). It is often associated with high morbidity and mortality, especially if it is resistant to intravascular volume expansion and conventional vasoconstrictive drugs [1]. This complication is similar to septic shock and characterized by severe and persistent hypotension, decreased systemic vascular resistance (SVR), normal or increased cardiac output (CO), low intra-cardiac filling pressures, and the necessity for high-dose catecholamines. Until today, the aetiology of VS is not fully understood. However, this syndrome is thought to be caused by the inflammatory-mediated dysregulation of endothelium homeostasis and subsequent endothelial dysfunction, including endothelial cell activation, endothelial permeability augmentation, coagulation defects, production of different regulators, and vascular tone disorders [1]. We read with great interest the paper by Kortekaas et al [2]. The authors report that pre-existing endothelial cell activation, reflected by higher baseline von Willebrand factor pro-peptide and soluble P-selectin levels is a predisposing factor for VS after mitral valve surgery. They also conclude that this activation may have resulted in desensibilization of endothelium in patients with VS. We would like to add some comments on possible agents for the management of VS VS is attributed to a combination of endothelial injury, arginine-vasopressin system dysfunction, and the release of vasodilatory inflammatory mediators[1]. Although these markers may be useful for the identification of patients at increased risk of developing VS, effective treatment strategies for this syndrome are currently lacking. The choice of vasoconstrictive agents for VS is a matter of controversy. To maintain adequate haemodynamics for VS, the conventional treatment based on fluid resuscitation and catecholamine drugs is ineffective in a subset of patients with profound vasodilatation[1]. Arginine vasopressin (AVP) and methylene blue (MB) may be used as additional rescue or a preventative treatment for VS [1, 3]. AVP is well-known to treat norepinephrine-resistant vasodilatation but may be associated rebound hypotension after discontinuation [3,4]. AVP significantly increases mean arterial pressure (MAP) and SVR, and results in a marked decrease in norepinephrine doses [1]. Tayama and associates [3] treated postoperative refractory low SVR hypotension concomitant with pulmonary hypertension by AVP. They reported that exogenous AVP normalized SVR and increased MAP. They also observed that AVP enhanced urine output and improved respiratory function. Noto and co-workers [4] reported that they treated six patients with terlipressin (TP; 1 mg bolus), a synthetic analogue of AVP for post-CPB refractory vasodilatory hypotension. In these patients, the authors suggested that exogenous TP administration normalized SVR and increased MAP with a minimum effect on pulmonary pressure. MB, an inhibitor of nitric oxide synthase and guanylate cyclase, seems to be a possible effective therapeutical option and to improve outcomes in patients with catecholamine-resistant VS after cardiac surgery [1, 5]. In a prospective observational study, Leyh and colleagues [5] tested the effect of MB (2 mg/kg over 20 minutes) in 54 patients with norepinephrine-resistant VS. In this study, MAP increased and norepinephrine dose decreased 1 hour after MB administration. These changes were accompanied by a significant decrease in CO. Finally, we think that further studies are necessary to find the most appropriate possible therapeutic agents for VS. Conflict of interest: none declared

Arginine vasopressin does not mediate heat loss in the tail of the rat

It has been reported that hypothermia induced by arginine vasopressin (AVP) is brought about by a coordinated response of reduced thermogenesis in brown adipose tissue (BAT) and increased heat loss through the tail of rats. However, it is well known that AVP is one of the strongest peripheral vasoconstrictors. Whether the AVP-induced hypothermia is associated with an increase in heat loss through the tail is questionable. Therefore, the present study assessed the relationship between the effects of AVP on tail skin temperature and the induced hypothermic response, and to determine if peripheral AVP administration increases heat loss from the tail. Core, BAT and tail skin temperature were monitored by telemetry in male Sprague–Dawley rats before and after intraperitoneal administration of AVP or vasopressin receptor antagonist. We also analyzed simultaneously of the time-course of AVP-induced hypothermic response and its relationship with changes in BAT temperature, and effect of AVP on grooming behavior. The key observations in this study were: (1) rats dosed with AVP induced a decrease in heat production (i.e., a reduction of BAT thermogenesis) and an increase of saliva spreading for evaporative heat loss (i.e., grooming behavior); (2) AVP caused a marked decrease in tail skin temperature and this effect was prevented by the peripheral administration of the vasopressin V1a receptor antagonist, suggesting that exogenous AVP does not increase heat loss in the tail of rats; (3) the vasopressin V1a receptor antagonist could elevate core temperature without affecting tail skin temperature, suggesting that endogenous AVP is involved in suppression of thermogenesis, but not mediates heat loss in the tail of rats. Overall, the present study does not support the conclusion of previous reports that AVP increased tail heat loss in rats, because AVP-induced hypothermia in the rat is accompanied by a decrease in tail skin temperature. The data indicate that exogenous AVP-induced hypothermia attributed to the suppression of thermoregulatory heat production and the increase of saliva spreading for evaporative heat loss.

Endogenous Angiotensin II‐induced p44/42 Mitogen‐Activated Protein Kinase Activation Mediates Sodium Appetite but not Thirst or Neurohypophysial Secretion in Male Rats

The renin-angiotensin-aldosterone system makes a critical contribution to body fluid homeostasis, and abnormalities in this endocrine system have been implicated in certain forms of hypertension. The peptide hormone angiotensin II (AngII) regulates hydromineral homeostasis and blood pressure by acting on both peripheral and brain targets. In the brain, AngII binds to the angiotensin type 1 receptor (AT1R) to stimulate thirst, sodium appetite and both arginine vasopressin (AVP) and oxytocin (OT) secretion. The present study used an experimental model of endogenous AngII to examine the role of p44/42 mitogen-activated protein kinase (MAPK) as a signalling mechanism to mediate these responses. Animals were given a combined treatment of furosemide and a low dose of captopril (furo/cap), comprising a diuretic and an angiotensin-converting enzyme inhibitor, respectively, to elevate endogenous AngII levels in the brain. Furo/cap induced p44/42 MAPK activation in key brain areas that express AT1R, and this effect was reduced with either a centrally administered AT1R antagonist (irbesartan) or a p44/42 MAPK inhibitor (U0126). Additionally, furo/cap treatment elicited water and sodium intake, and irbesartan markedly reduced both of these behaviours. Central injection of U0126 markedly attenuated furo/cap-induced sodium intake but not water intake. Furthermore, p44/42 MAPK signalling was not necessary for either furo/cap- or exogenous AngII-induced AVP or OT release. Taken together, these results indicate that p44/42 MAPK is required for AngII-induced sodium appetite but not thirst or neurohypophysial secretion. This result may allow for the discovery of more specific downstream targets of p44/42 MAPK to curb sodium appetite, known to exacerbate hypertension, at the same time as leaving thirst and neurohypophysial hormone secretion undisturbed.

Urine-concentrating defects exacerbate with age in male offspring with a low-nephron endowment

Fetal uninephrectomy (uni-x) in male sheep at 100 days of gestation (term = 150 days) reduces overall nephron endowment without affecting birth weight. Offspring have a lower glomerular filtration rate (GFR) and elevated mean arterial pressure (MAP) at 6 mo of age. This study investigated whether this reduction in renal function was associated with impaired urine-concentrating ability at 6 mo of age and exacerbated with ageing (4 yr) and examined response to 1) nonpressor dose of exogenous arginine vasopressin (AVP; 0.2 μg·kg(-1)·h(-1) iv) and 2) 30 h of water deprivation. Basal MAP was higher in uni-x animals at both ages, and became further elevated with age compared with the sham group (elevation in MAP with age; sham: ~4 mmHg, uni-x: 9 mmHg, P(group × age) < 0.01). GFR declined with ageing in both groups with the decrease being greater with age in the uni-x group (further 26%, P(group × age) < 0.001). In response to AVP infusion, urine osmolality increased in both treatment groups; this response was significantly lower in the uni-x animals and became further reduced with ageing. Uni-x animals had reduced renal expression of vasopressin-2 receptor and aquaporin-2 at both ages (P < 0.01). The increase in plasma AVP levels in response to dehydration was similar between the treatment groups, suggesting the urine-concentrating defect was associated with these renal gene changes rather than defects in AVP secretion. Renal insufficiency due to a low-nephron endowment increases the risk of hypertension and chronic renal disease and may incur greater vulnerability to physiological challenges such as water deprivation as observed in the uni-x animals.

Detectability of Vasopressin in Continuous Venovenous Hemodialysis Effluent of Patients with Vasodilatory Shock Treated with Exogenous Arginine Vasopressin

To determine whether vasopressin is detectable in the continuous venovenous hemodialysis (CVVHD) effluent of patients receiving exogenous arginine vasopressin, and to determine whether treatment-specific factors are associated with vasopressin levels in CVVHD effluent. DESIGN. Prospective observational study. SETTING. Intensive care units of a tertiary care academic medical center. PATIENTS. Twenty-seven adults with vasodilatory shock who received a stable-dose continuous intravenous infusion of arginine vasopressin with concomitant uninterrupted CVVHD for at least 4 hours between September 2008 and May 2010. MEASUREMENTS AND MAIN RESULTS. Vasopressin levels in CVVHD effluent were assessed by radioimmunoassay. Statistical analysis was performed with analysis of variance and Pearson correlation. A multivariate linear regression was used to assess for independent factors associated with vasopressin levels in CVVHD effluent. The CVVHD effluent of all patients was assessed for vasopressin levels. The median exogenous arginine vasopressin dose was 0.03 unit/minute (range 0.02-0.18 unit/min), whereas the median CVVHD effluent flow rate was 22.6 ml/kg/hour (interquartile range [IQR] 21.5-26.8 ml/kg/hr). Vasopressin was detectable in all effluent samples (median 88.8 pg/ml, IQR 36.4-113.7 pg/ml). There were no significant differences in CVVHD effluent vasopressin levels among CVVHD filter types (p=0.39). The CVVHD effluent vasopressin levels correlated with exogenous arginine vasopressin dose (r2=0.49, p<0.001). After adjustment for CVVHD effluent flow rate and administration of corticosteroids, with multivariate linear regression, only exogenous arginine vasopressin dose was independently associated with CVVHD effluent vasopressin level. CONCLUSION. Vasopressin is detectable in CVVHD effluent, suggesting that it is removed by CVVHD. In addition, exogenous arginine vasopressin infusion dose is independently associated with CVVHD effluent vasopressin level.

Vasopressin needs an audience: Neuropeptide elicited stress responses are contingent upon perceived social evaluative threats

The nonapeptide arginine vasopressin (AVP) plays an important role in hypothalamus–pituitary–adrenal axis regulation and also functions as a social hormone in a wide variety of species, from voles to humans. In the current report we use a variety of stress inducing tasks, including the Trier Social Stress Test (TSST) and intranasal administration of AVP to show that intranasal administration of this neuropeptide leads to a significant increase in salivary cortisol and pulse rate, specifically in conditions where subjects perform tasks in the presence of a social evaluative threat (task performance could be negatively judged by others). In contrast, in conditions without a social evaluative threat (no task condition, modified TSST without audience and bike ergometry), subjects receiving AVP did not differ from subjects receiving placebo. Thus exogenous AVP's influence is contingent upon a circumscribed set of initial conditions that constitute a direct threat to the maintenance of our social selves. Stress evoked by social threat is an integral part of social life and is related to self-esteem and in extreme forms, to poor mental health (e.g., social phobia). Our findings suggest that AVP is a key component in the circuit that interlaces stress and social threat and findings offer inroads to our understanding of individual differences in sociability and in stress response elicited in threatening social situations.

Use of pressor therapy in 34 hypotensive critically ill neonatal foals

Arginine vasopressin (AVP) is used in human medicine in the management of vasodilatory shock and cardiac arrest, but it is not widely used in equine neonatal intensive care because of concerns about potential side effects and suboptimal efficacy. This retrospective study reports the clinical use of AVP and norepinephrine (NE) in foals with refractory hypotension. To report the cardiovascular responses and fluid balance in critically ill, hypotensive foals receiving either NE or AVP. The medical records of neonatal foals (<7 days of age) from 2000 to 2007 admitted to the Marion duPont Scott Equine Medical Center were reviewed. The use of exogenous AVP infusion was associated with a significant increase in mean arterial pressure (MAP) and urinary output, and a significant decrease in heart rate. NE administration was also associated with a significant increase in MAP. The findings of this first report of the clinical treatment of foals with refractory hypotension support the use of AVP and NE.

Relative deficiency of arginine vasopressin in children after cardiopulmonary bypass*

To describe changes in plasma arginine vasopress in concentration in children following cardiopulmonary bypass and determine whether, in some patients, plasma arginine vasopressin remains relatively low despite hemodynamic instability. Prospective observational study. Pediatric intensive care unit at a tertiary care university hospital. One hundred twenty patients ≤ 18 yrs of age undergoing open heart surgery requiring cardiopulmonary bypass at Children's Hospital of Michigan between January 2008 and January 2009. Blood samples were collected before cardiopulmonary bypass and 4, 24, and 48 hrs after cardiopulmonary bypass for measurement of plasma arginine vasopressin concentration. Mean plasma arginine vasopressin (pg/mL) for all patients was 21 ± 63 before cardiopulmonary bypass and 80 ± 145, 43 ± 79, and 19 ± 25 at 4, 24, and 48 hrs, respectively, after cardiopulmonary bypass. Patients with plasma arginine vasopressin below the lower quartile (< 9.2 pg/mL) at 4 hrs after cardiopulmonary bypass (n = 29), labeled group A, were examined separately and compared with the rest of the study population, labeled group B. Mean plasma arginine vasopressin was 4.9 ± 2.6 in group A at 4 hrs after cardiopulmonary bypass, statistically unchanged from its baseline mean plasma arginine vasopressin of 5.0 ± 10.4 (p = .977). Mean plasma arginine vasopressin in group B was 104 ± 160 at 4 hrs after cardiopulmonary bypass. Mean plasma arginine vasopressin of group A was also significantly lower as compared with group B before and 24 and 48 hrs after cardiopulmonary bypass. Hemodynamics, inotrope score, and serum sodium did not differ between groups at any time point. Plasma arginine vasopressin was measured immediately before exogenous arginine vasopressin administration in 10 patients; only those (n = 3) with hemodynamic instability and relatively low plasma arginine vasopressin concentration (< 9.2 pg/mL) had notable hemodynamic improvement. In some children undergoing open heart surgery, plasma arginine vasopressin concentration is relatively low at baseline and remains low after cardiopulmonary bypass regardless of hemodynamic stability and serum osmolality. These children are likely the optimal candidates for exogenous arginine vasopressin should hemodynamic compromise occur.

Arginine vasopressin plasma levels could indicate childern undergoing cardiopulmonary bypass that might benefit from exogenous arginine vasopressin*

Arginine vasopressin plasma levels could indicate childern undergoing cardiopulmonary bypass that might benefit from exogenous arginine vasopressin*

Plasma arginine vasopressin concentration in horses undergoing surgery for colic

To determine if horses before undergoing anesthesia for surgical correction of colic would have lower plasma arginine vasopressin (AVP) concentrations than healthy horses undergoing anesthesia for arthroscopic surgery, and would not increase their plasma AVP concentrations in response to anesthesia and surgery. Prospective clinical study. University teaching hospital. Fourteen horses with colic and 8 healthy horses. Horses with colic underwent anesthesia and surgery for alleviation of colic, and healthy horses underwent anesthesia and surgery for arthroscopy. Plasma AVP was measured perioperatively in horses with colic and in healthy horses. Before anesthesia, and 30 and 60 minutes after induction, horses with colic had greater median plasma AVP concentrations than control horses (P<or=0.001); thereafter during anesthesia differences in AVP concentrations between the 2 groups were not significant. In the control group, plasma AVP concentration increased during 120 minutes of anesthesia; no such increase occurred in colic horses. Compared with healthy horses, horses with colic had higher preanesthesia plasma AVP concentrations that did not increase further in response to anesthesia and surgery. Exogenous AVP is associated with decreased splanchnic perfusion in a variety of animal species and, therefore, could be detrimental to horses with colic. Thus, it may be inappropriate to use exogenous AVP in support of blood pressure in anesthetized horses with colic. Further studies are warranted to define appropriate indications for the use of AVP in horses with colic.