Plasma Arginine Vasopressin Concentrations Research Articles

The Influence of Rehydration Mode After Exercise Dehydration on Cardiovascular Function

Our purpose was to compare the common modes of rehydration (REHY) on cardiovascular and fluid regulation recovery after exercise dehydration (EXDE). Twelve nonheat-acclimatized trained subjects (age: 23 ± 4 years, weight: 81.3 ± 3.7 kg, height: 180 ± 6 cm, V[Combining Dot Above]O2max: 56.9 ± 4.4 ml·min·kg , and body fat: 7.8 ± 3.0%) completed 20-hour fluid restriction and 2-hour EXDE to -4% body mass, and then were rehydrated to -2% body mass in a randomized, crossover design. The REHY methods included no fluid (NF), ad libitum, oral (OR), intravenous (IV), and a combination of IV and OR (IV + OR) of 1/2-normal saline (0.45% NaCl). The REHY occurred for 30 minutes, and the subjects were observed during rest for 30 minutes. Seated, standing, and mean arterial pressure (MAP) and blood pressure (BP) were measured every 15 minutes throughout REHY. Heart rate (HR), plasma arginine vasopressin concentration [AVP], and thirst perception were measured throughout REHY. The EXDE resulted in a body mass loss of 4.32 ± 0.22%. The REHY returned the subjects to -2.13 ± 0.47% body mass for controlled trials. Seated systolic BP was greater for IV + OR compared with that for OR (p = 0.015). Seated systolic BP and MAP during REHY showed that IV + OR was greater than OR, independent of time (p ≤ 0.011). Upon standing, IV + OR demonstrated a greater BP than both NF (p = 0.012) and OR (p = 0.031) did. The HR was reduced by IV and IV + OR to a greater extent than NF at REHY30 and REHY60 (p < 0.05). The IV + OR [AVP] demonstrated a strong trend for decreasing over time (p = 0.054) and was significantly less than NF at REHY60 (p = 0.003). Practical application seeking to restore cardiovascular function after EXDE, the combined use of IV + OR rather than a single REHY method seems to be most expedient.

P2.072 Seek and You Shall Find - Value of Extragenital Chlamydia and Gonorrhoea TMA Testing in a Cohort of MSM

<h3>AIM</h3> To examine the effect of intravascular volume expansion for the treatment of hypovolaemia in sick preterm neonates. <h3>METHODS</h3> An intravenous infusion of 20 ml per kg of 4.5 % albumin was given to 14 preterm neonates. The effects on systolic blood pressure, central peripheral temperature difference (c-pT), and plasma arginine vasopressin concentration (pAVP) were measured. <h3>RESULTS</h3> Thirteen babies showed a rise in systolic blood pressure. The six babies with the highest initial values of pAVP and c-pT showed a fall in both of these after infusion. The babies with lower initial pAVP (below 4 pmol/l) showed either a rise (two) or no change (six) after albumin infusion. There was a significant correlation between c-pT and log pAVP before (r²=0.61; p&lt;0.05) and after infusion (r²=0.45; p&lt;0.05). <h3>CONCLUSIONS</h3> Plasma AVP concentration is related to c-pT in unwell preterm newborns. This study suggests that clinical assessment of hypovolaemia in preterm newborns is poor and could be improved by using c-pT.

Study on intervention effect of Danggui Shaoyao San on rats with cirrhotic ascites

To investigate the intervention effect of Danggui Shaoyao San on rats with cirrhotic ascites, and discuss the effect of arginine vasopressin (AVP) on cirrhotic ascites. Male SD rats were randomly divided into the control group, the model group, Danggui Shaoyao San low, middle and high dose groups. The cirrhotic ascites rat model was established by CCl4 combined with phenobarbital. Their urines were collected at 24 h to observe urine excretion of each group. Filter papers were used to determine the amount of ascites. The levels of serum alanine aminotransferasa (ALT) , aspartate aminotransferase (AST) were detected by the automatic biochemistry analyzer. Plasma prothrombin time (PT) was evaluated by the blood coagulation analyzer. The concentration of AVP in plasma was detected by enzyme-linked immunosorbent assay (ELISA). Pathological changes in livers were observed by HE staining. Compared with the model group, the Danggui Shaoyao San group showed significant improvement in live indexes, with notable decrease in serum ALT and AST and the time of PT, improvement in liver pathological changes. Simultaneously, the amount of ascites decreased to varying degrees, with notable increase in urine in 24 h and decrease in AVP concentration in plasma. Danggui Shaoyao San can notably improve liver functions of rats with cirrhotic ascites, reduce the generation of ascites and delay the progress of liver pathological changes. Its mechanism may be related to AVP.

Effects of imidapril treatment on aquaporin-2 expression in the kidneys and excretion in the urine of hypertensive rats.

Renal aquaporin-2 (AQP2) is critical for maintaining water balance and is associated with hypertension. Anti-hypertensive drugs, including imidapril, improve kidney function; however, it remains unclear whether these effects are mediated through the regulation of AQP2. In this study, the effects of imidapril on AQP2 expression in the kidneys and excretion in urine were assessed in hypertensive rats. Hypertension was induced in 24 rats, which were randomized into a control group, treated with water only, and an imidapril treatment group (n=12 per group). Blood and urine samples were collected from all rats to determine blood pressure (BP), serum Na+, urine volume and urine osmolality after 8 weeks of treatment. Molecular and immunological techniques were used to measure the expression of AQP2 in the kidneys. Urine AQP2 concentration was detected by indirect enzyme-linked immunosorbent assay (ELISA). The concentration of plasma arginine vasopressin (AVP), a regulator of AQP2 was detected by radioimmunoassay (RIA). Hypertensive rats treated with imidapril exhibited reduced BP and 24-h urine osmolality, with a concomitant increase in 24-h urine volume, compared with control hypertensive rats (P<0.05). Additionally, the expression of Aqp2 mRNA, detected by RT-PCR, and AQP2 protein, detected by immunohistochemistry and western blotting, in renal tissue significantly decreased (P<0.05). Finally, urine AQP2 concentration increased while plasma AVP concentration decreased following imidapril treatment (P<0.05). These findings indicate that imidapril reduces the expression level of AQP2 in renal tissue and accelerates its excretion.

Comparison of the diuretic effects of medetomidine hydrochloride and xylazine hydrochloride in healthy cats

To investigate dose-related diuretic effects of medetomidine hydrochloride and xylazine hydrochloride in healthy cats. 5 sexually intact cats (4 males and 1 female). The 5 cats received each of 11 treatments. Cats were treated by IM administration of saline (0.9% NaCl) solution (control treatment), medetomidine hydrochloride (20, 40, 80, 160, and 320 μg/kg), and xylazine hydrochloride (0.5, 1, 2, 4, and 8 mg/kg). Urine and blood samples were collected 9 times during a 24-hour period. Variables measured were urine volume, pH, and specific gravity; plasma arginine vasopressin (AVP) concentration; and creatinine and electrolyte concentrations as well as osmolality in both urine and plasma. Both medetomidine and xylazine increased urine production for up to 5 hours after injection. Xylazine had a dose-dependent diuretic effect, but medetomidine did not. Urine specific gravity and osmolality decreased in a dose-dependent manner for both drugs. Free-water clearance increased for up to 5 hours after injection, whereas glomerular filtration rate, osmolar clearance, plasma osmolality, and electrolyte concentrations did not change significantly. Area under the curve for AVP concentrations decreased in a dose-dependent manner for medetomidine but not for xylazine; however, this was not related to diuresis. Both medetomidine and xylazine induced profound diuresis in cats by decreasing reabsorption of water in the kidneys. The diuretic effect of medetomidine, including the change in AVP concentration, differed from that of xylazine. Care must be used when administering these drugs to cats with urinary tract obstruction, hypovolemia, or dehydration.

Copeptin as a marker of relative arginine vasopressin deficiency after pediatric cardiac surgery

Relative arginine vasopressin (AVP) deficiency after pediatric cardiac surgery has recently been described. Copeptin, a more stable and easily measured product of pro-AVP processing, may be a means of identifying these patients. We aimed to determine if copeptin was correlated with AVP in these children and whether it can be a surrogate marker of relative AVP deficiency. Patients <6 years of age with basic Aristotle scores ≥7 requiring surgery with cardiopulmonary bypass were prospectively enrolled. Plasma AVP and copeptin concentrations were measured pre-cardiopulmonary bypass and 4 and 24 h post-cardiopulmonary bypass. Relative AVP deficiency was defined a priori based on our previous work as AVP <9.2 pg/ml at 4 h post-cardiopulmonary bypass. Of 41 children enrolled, relative AVP deficiency was present in 13 (32 %). AVP and copeptin concentrations were significantly lower in these 13 children at 4 h post-cardiopulmonary bypass as compared to the other 28 patients. A significant positive association between plasma AVP and copeptin concentrations over time was determined. Based on log-transformed analyses, a 1 % increase in plasma AVP led to a 0.19 % increase in copeptin. Further, copeptin <1.12 ng/ml at 4 h post-cardiopulmonary bypass had a sensitivity of 92 % and a negative predictive value of 95 % for relative AVP deficiency. Plasma AVP and copeptin are positively associated in children undergoing cardiac surgery. Copeptin may represent a useful means of identifying relative AVP deficiency in these patients.

Effect of intranasal arginine vasopressin on human headache

Arginine vasopressin (AVP), a nonapeptide hormone of posterior pituitary, reaches the central nervous system from systemic blood circulation with a difficulty because of the blood–brain barrier (BBB). The interest has been expressed in the use of the nasal route for delivery of AVP to the brain directly, exploiting the olfactory pathway. Our previous study has demonstrated that AVP in the brain rather than the spinal cord and blood circulation plays an important role in rat pain modulation. For understanding the role of AVP on pain modulation in human, the communication tried to investigate the effect of intranasal AVP on human headache. The results showed that (1) AVP concentration in both plasma and cerebrospinal fluid (CSF) increased significantly in headache patients, who related with the headache level; (2) there was a positive relationship between plasma and CSF AVP concentration in headache patients; and (3) intranasal AVP could relieve the human headache in a dose-dependent manner. The data suggested that intranasal AVP, which was delivered to the brain through olfactory region, could treat human headache and AVP might be a potential drug of pain relief by intranasal administration.

Hydration biomarkers in free-living adults with different levels of habitual fluid consumption

Little is known about the impact of habitual fluid intake on physiology. Specifically, biomarkers of hydration status and body water regulation have not been adequately explored in adults who consume different fluid volumes in everyday conditions, without prolonged exercise or environmental exposure. The purpose of the present study was to compare adults with habitually different fluid intakes with respect to biomarkers implicated in the assessment of hydration status, the regulation of total body water and the risk of kidney pathologies. In the present cross-sectional study, seventy-one adults (thirty-two men, thirty-nine women, age 25–40 years) were classified according to daily fluid intake: thirty-nine low drinkers (LD; ≤ 1·2 litres/d) and thirty-two high drinkers (HD; 2–4 litres/d). During four consecutive days, urinary parameters (first morning urine (FMU) on day 1 and subsequent 24 h urine (24hU) collections), blood parameters, and food and beverage intake were assessed. ANOVA and non-parametric comparisons revealed significant differences between the LD and HD groups in 24hU volume (1·0 (se 0·1) v. 2·4 (se 0·1) litres), specific gravity (median 1·023 v. 1·010), osmolality (767 (se 27) v. 371 (se 33) mOsm/kg) and colour (3·1 (se 0·2) v. 1·8 (se 0·2)). Similarly, in the FMU, the LD group produced a smaller amount of more concentrated urine. Plasma cortisol, creatinine and arginine vasopressin concentrations were significantly higher among the LD. Plasma osmolality was similar between the groups, suggesting physiological adaptations to preserve plasma osmolality despite low fluid intake. The long-term impact of adaptations to preserve plasma osmolality must be examined, particularly in the context of renal health.

Hypothalamic vasopressin system regulation by maternal separation: Its impact on anxiety in rats

Maternal separation (MS) has been used to model the causal relationship between early life stress and the later stress-over-reactivity and affective disorders. Arginine vasopressin (AVP) is among several factors reported to be abnormal. The role of AVP on anxiety is still unclear. In order to further investigate this causal relationship and its possible role in anxiogenesis, male rat pups were separated from their dams for 3h daily (3hMS) from post-natal day (PND) 2 to PND15. Fos expression in AVP+ neurons in the hypothalamic paraventricular (PVN) and supraoptic nuclei (SON) triggered by 3hMS, and AVP-mRNA expression, were examined at PND10 and PND21 respectively, whereas AVP-mRNA expression, PVN and SON volumes and plasma AVP concentration were assessed in adulthood. Elevated plus maze test (EPM) and Vogel conflict test (VCT) were also performed to evaluate unconditioned and conditioned anxious states at PND70–75. At PND10, a single 3hMS event increased Fos expression in AVP+ neurons fourfold in PVN and six to twelvefold in SON. AVP-mRNA was over-expressed in whole hypothalamus, PVN and SON between 122% and 147% at PND21 and PND63. Volumes of AVP-PVN and AVP-SON measured at PND75 had marked increases as well as AVP plasma concentration at 12h of water deprivation (WD). MS rats demonstrated a high conditioned anxious state under VCT paradigm whereas no difference was found under EPM. These data demonstrate direct relationships between enhanced AVP neuronal activation and a potentiated vasopressin system, and this latter one with high conditioned anxiety in MS male rats.

Ionotropic Glutamate Receptors in Hypothalamic Paraventricular and Supraoptic Nuclei Mediate Vasopressin and Oxytocin Release in Unanesthetized Rats

We report changes in plasma arginine vasopressin (AVP) and oxytocin (OT) concentrations evoked by the microinjection of l-glutamate (l-glu) into the hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) of unanesthetized rats, as well as which local mechanisms are involved in their mediation. l-Glu microinjection (10 nmol/100 nl) into the SON increased the circulating levels of both AVP and OT. The AVP increases were blocked by local pretreatment with the selective non-N-methyl-d-aspartate (NMDA) receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX) (2 nmol/100 nl), but it was not affected by pretreatment with the NMDA-receptor antagonist LY235959 (2 nmol/100 nl). The OT response to l-glu microinjection into the SON was blocked by local pretreatment with either NBQX or LY235959. Furthermore, the administration of either the non-NMDA receptor agonist (±)-α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid hydrobromide (AMPA) (5 nmol/100 nl) or NMDA receptor agonist NMDA (5 nmol/100 nl) into the SON had no effect on OT baseline plasma levels, but when both agonists were microinjected together these levels were increased. l-Glu microinjection into the PVN did not change circulating levels of either AVP or OT. However, after local pretreatment with LY235959, the l-glu microinjection increased plasma levels of the hormones. The l-glu microinjection into the PVN after the local treatment with NBQX did not affect the circulating AVP and OT levels. Therefore, results suggest the AVP release from the SON is mediated by activation of non-NMDA glutamate receptors, whereas the OT release from this nucleus is mediated by an interaction of NMDA and non-NMDA receptors. The present study also suggests an inhibitory role for NMDA receptors in the PVN on the release of AVP and OT.

Apelin is involved in postprandial responses and stimulates secretion of arginine-vasopressin, adrenocorticotropic hormone, and growth hormone in the ruminant

Apelin and its mRNA are expressed in several tissues, including the supraoptic and paraventricular nuclei in the hypothalamus. Although apelin is reported to be involved in the regulation of fluid homeostasis, little is known about the postprandial dynamics of apelin in plasma and its regulatory effects on the anterior pituitary hormones of ruminants. Therefore, the aims of this study were to investigate the following: (1) changes in plasma apelin concentrations in response to food intake under conditions of hydration (free access to water) or dehydration (water restriction), and (2) the effects of intravenous administration of apelin on plasma concentrations of arginine-vasopressin (AVP), ACTH, GH, and insulin. In Experiment 1 with the use of goats, the postprandial plasma apelin concentration was significantly increased under the dehydration condition compared with the hydration condition, and this increase was accompanied by increased plasma concentrations of AVP and ACTH after 24 h of dehydration. In Experiment 2 with the use of sheep and hydration conditions, the intravenous administration of apelin ([Pyr1]-apelin-13; 0.5 mg/head) caused a tendency to increase or caused a significant increase in plasma concentrations of AVP, ACTH, GH, insulin, and glucose. On the basis of these findings, we concluded that apelin is involved in the feeding process, and it regulates endocrine functions in the anterior pituitary gland via AVP in ruminant animals.

Effects of Tolvaptan on Systemic and Renal Hemodynamic Function in Dogs with Congestive Heart Failure

We investigated the effects of tolvaptan, a vasopressin V(2)-receptor antagonist, on diuretic response and systemic and renal hemodynamic characteristics in conscious dogs with congestive heart failure (CHF). We also compared these effects with those of furosemide, a loop diuretic. CHF was induced by rapid right-ventricular pacing at 260 beats/min for at least 3 weeks, and maintained with a pacing rate of 220-240 beats/min. CHF dogs were orally given tolvaptan (10 mg/kg), furosemide (10 mg/kg) and vehicle in random order during the stable CHF state. Urine excretion, systemic and renal hemodynamic parameters, and plasma hormone levels were measured over 6-hour periods after drug administration. Tolvaptan induced aquaresis with an increase in free water clearance, resulting in a significant increase in serum sodium concentrations and a decrease in cumulative water balance. Tolvaptan also decreased pulmonary capillary wedge pressure without affecting systemic vascular resistance, glomerular filtration rate or renal blood flow. Tolvaptan tended to increase plasma arginine vasopressin concentrations but did not affect plasma renin activity. In contrast, furosemide induced clear saluresis with increased electrolyte excretion, resulting in decreased pulmonary capillary wedge pressure. However, furosemide also decreased serum potassium concentration and increased plasma arginine vasopressin concentrations and plasma renin activity. Tolvaptan elicited a potent aquaretic response and reduced the cardiac preload without unfavorable effects on systemic or renal hemodynamics, the renin-angiotensin-aldosterone system, or the sympathetic nervous system in CHF dogs. Thus, tolvaptan may offer a novel approach to remove excess water congestion from patients with CHF.

Behavioral and endocrine effects of chronic exposure to low doses of chlorobenzenes in Wistar rats

Chlorobenzenes have often been applied to study persistent organic pollutants with endocrine disruptor effects (POP/EDCs), but with the focus mainly on physiological aspects. Few data exist on the effects of chlorobenzenes and most POP/EDCs on anxiety or other arginine-vasopressin (AVP)- and oxytocin (OXT)-mediated behavior, albeit exposure to POP/EDCs or their ambient mixtures, even in low doses, may pose health risks for subjects living in contaminated areas and/or consuming polluted food. Our primary aim was therefore to demonstrate behavioral effects of longterm exposure to a discrete dose of a chlorobenzene mixture, and to draw attention to the results of subtoxic oral exposure on anxiety-related elements and the possible underlying endocrine processes. Adult male Wistar rats were treated daily with a mixture (ClB) of 1μg/kg each of hexachlorobenzene and 1,2,4-trichlorobenzene via a gastric tube for 30, 60 or 90days. After exposure, anxiety-related behavioral elements were determined in open-field and elevated plus maze tests. At euthanasia, the plasma levels of AVP, OXT and adrenocorticotrophic hormone (ACTH) were measured. Simultaneously, pituicytes from subjects were cultured to study the levels of basal and serotonin- or norepinephrinestimulated AVP and OXT secretion. Various anxiety-related behavioral elements were observed to be increased in both tests. The plasma AVP, OXT and ACTH concentrations were increased, to extents depending on the duration of exposure. The basal and monoamine-stimulated levels of AVP and OXT secretion of pituicytes prepared from the ClB-exposed rats were also elevated. Thus, certain anxietyrelated behavioral and endocrine elements were modulated by long-term exposure to ClB. As adult subjects were involved, which are generally less susceptible to toxic agents, it may be concluded that discrete doses of POP/EDC chlorobenzenes that are low enough to fall below the range of legal regulation may exert anxiogenic effects, which suggests that certain anxiogenic disorders may be induced environmentally in exposed human populations.

An Intervention Study of Oral Versus Intravenous Hypertonic Saline Administration in Ultramarathon Runners With Exercise-Associated Hyponatremia: A Preliminary Randomized Trial

To determine whether asymptomatic exercise-associated hyponatremia (EAH) in ultramarathon runners can be corrected with either oral or intravenous (IV) 3% hypertonic saline (HTS). Prospective with randomization into 1 of 2 intervention arms. Western States (161 km) Endurance Run, California. Forty-seven finishers in the event consented to be screened to identify those with EAH, defined as plasma sodium ([Na]p) <135 mmol/L at race end. Participants with EAH but without symptoms were randomized to receive a single 100 mL dose of either oral or IV 3% HTS. Blood was drawn before intervention and at 60 minutes postintervention to measure [Na]p, and concentrations of plasma potassium, proteins, and arginine vasopressin (AVP). Body mass, percent total body water, and percent body fat were measured prerace and postrace using impedance scales. Change in [Na]p. Fourteen of 47 consenting finishers (30%) had EAH. Eight agreed to be randomized into the intervention protocol. Only in the IV group did [Na]p change significantly (from 130.8 to 134.6 mmol/L) over the 60 minutes post-HTS administration. Elevated AVP concentrations were seen at race finish in both the groups and remained so after HTS treatment. In this preliminary trial, prompt administration of a 100 mL bolus of IV 3% HTS was associated with normalization of [Na]p in asymptomatic EAH, but a similar effect was not demonstrated for the same dose orally. Elevated AVP levels were observed and may play a part in the development of EAH but were not suppressed significantly by either intervention.

Vasopressin-dependent coupling between sodium transport and water flow in a mouse cortical collecting duct cell line

Water balance is achieved through the ability of the kidney to control water reabsorption in the connecting tubule and the collecting duct. In a mouse cortical collecting duct cell line (mCCD(c11)), physiological concentrations of arginine vasopressin increased both electrogenic, amiloride-sensitive, epithelial sodium channel (ENaC)-mediated sodium transport measured by the short-circuit current (Isc) method and water flow (Jv apical to basal) measured by gravimetry with similar activation coefficient K(1/2) (6 and 12 pM, respectively). Jv increased linearly according to the osmotic gradient across the monolayer. A small but highly significant Jv was also measured under isoosmotic conditions. To test the coupling between sodium reabsorption and water flow, mCCD(c11) cells were treated for 24 h under isoosmotic condition with either diluent, amiloride, vasopressin or vasopressin and amiloride. Isc, Jv, and net chemical sodium fluxes were measured across the same monolayers. Around 30% of baseline and 50% of vasopressin-induced water flow is coupled to an amiloride-sensitive, ENaC-mediated, electrogenic sodium transport, whereas the remaining flow is coupled to an amiloride-insensitive, nonelectrogenic sodium transport mediated by an unknown electroneutral transporter. The mCCD(c11) cell line is a first example of a mammalian tight epithelium allowing quantitative study of the coupling between sodium and water transport. Our data are consistent with the 'near isoosmotic' fluid transport model.

Post cardiac surgery vasoplegia is associated with high preoperative copeptin plasma concentration

IntroductionPost cardiac surgery vasodilatation (PCSV) is possibly related to a vasopressin deficiency that could relate to chronic stimulation of adeno-hypophysis. To assess vasopressin system activation, a perioperative course of copeptin and vasopressin plasma concentrations were studied in consecutive patients operated on for cardiac surgery.MethodsSixty-four consecutive patients scheduled for elective cardiac surgery with cardiopulmonary bypass were studied. Hemodynamic, laboratory and clinical data were recorded before and during cardiopulmonary bypass, and at the eighth postoperative hour (H8). At the same time, blood was withdrawn to determine plasma concentrations of arginine vasopressin (AVP, radioimmunoassay) and copeptin (immunoluminometric assay). PCSV was defined as mean arterial blood pressure < 60 mmHg with cardiac index ≥ 2.2 l/min/m2, and was treated with norepinephrine to restore mean blood pressure > 60 mmHg. Patients with PCSV were compared with the other patients (controls). Student's t test, Fisher's exact test, or nonparametric tests (Mann-Whitney, Wilcoxon) were used when appropriate. Correlation between AVP and copeptin was evaluated and receiver-operator characteristic analysis assessed the utility of preoperative copeptin to distinguish between controls and PCSV patients.ResultsPatients who experienced PCSV had significantly higher copeptin plasma concentration before cardiopulmonary bypass (P < 0.001) but lower AVP concentrations at H8 (P < 0.01) than controls. PCSV patients had preoperative hyponatremia and decreased left ventricle ejection fraction, and experienced more complex surgery (redo). The area under the receiver-operator characteristic curve of preoperative copeptin concentration was 0.86 ± 0.04 (95% confidence interval = 0.78 to 0.94; P < 0.001). The best predictive value for preoperative copeptin plasma concentration was 9.43 pmol/l with a sensitivity of 90% and a specificity of 77%.ConclusionsHigh preoperative copeptin plasma concentration is predictive of PSCV and suggests an activation of the AVP system before surgery that may facilitate depletion of endogenous AVP stores and a relative AVP deficit after surgery.

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.

DEHYDRATION ENCEPHALOPATHY: A NEUROLOGICAL EMERGENCY IN THE OLDER ADULTS

DEHYDRATION ENCEPHALOPATHY: A NEUROLOGICAL EMERGENCY IN THE OLDER ADULTS

Central Administration of Kisspeptin-10 Inhibits Water and Sodium Excretion of Anesthetized Male Rats and the Involvement of Arginine Vasopressin

Aim. To investigate the effect of hypothalamus kisspeptin on water and sodium excretion and the possible mechanism. Method. The intracerebroventricular (icv) administration and radioimmunoassay were used to observe the effect of kisspeptin-10 on urine flow, sodium and potassium excretion, plasma arginine vasopressin (AVP), and atrial natriuretic peptide (ANP) concentrations in anesthetized male rats. The mediation of renal sympathetic nerve was also investigated by studies conducted on rats with bilateral renal sympathetic denervation. Results. The urine flow, sodium excretion, and free water clearance decreased significantly by icv injection of 5 nmol kisspeptin-10 (p < 0.05) from 30 to 60 min post-injection. Meanwhile, plasma AVP concentrations increased significantly 30 min after the icv injection of 5 nmol kisspeptin-10 (p < 0.05), whereas the equal dose of kisspeptin-10 did not significantly change plasma ANP concentrations. The mean arterial blood pressure, heart rate, and potassium excretion did not significantly change during the experiment. Furthermore, pretreatment with 5 nmol kisspeptin-10 could still significantly decrease urine flow and sodium excretion in renal sympathetic denervated rats. Conclusion. Central administration of kisspeptin-10 could inhibit sodium excretion and urine flow in anesthetized male rats, which is probably mediated by increasing the plasma AVP concentration and is independent of plasma ANP concentration and renal sympathetic nerve activity.

Support for two increased vasopressinergic activities in depression at large and the differential effect of antidepressant treatment

Animal models of depression support a pathogenetic role for vasopressinergic activation involving increased arginine vasopressin (AVP) release and AVP receptor (V1b) synthesis. Evidence of this has been found particularly in patients with highly anxious-retarded (HAR) and above-normal AVP (ANA) depression. A general pathogenetic theory however predicts vasopressinergic activities to play a role in at least all major depressive disorders, and antidepressant (AD) treatment to be mediated by vasopressinergic reduction. We tested these hypotheses by re-analysing the data of 66 depressed patients; 27 with and 39 without AD treatment. The plasma AVP concentration and the AVP-cortisol correlation were used as presumed parameters of AVP release and pituitary V1b receptor function. A high AVP-cortisol correlation (r = 0.72; p < 0.001) was found in the non-AD group, and no correlation in the AD treatment group. AD treatment did not relate to plasma AVP concentration. The AVP-cortisol correlation in HAR and ANA depression was not explained by a low rate of AD treatment. These human data support the hypothesis of increased AVP release and receptor function as pathogenetic characteristics of major depression, and show selective normalization of the AVP-cortisol correlation, which is supposed to reflect the receptor function, by AD treatment.