Antidiuretic Hormone Receptor Antagonists ; Heart Failure ; drug therapy ; Humans

Animals ; Antidiuretic Hormone Receptor Antagonists ; Body Temperature ; drug effects ; Chlorpyrifos ; toxicity ; Female ; Hypothermia ; chemically induced ; Male ; Rats ; Rats, Sprague-Dawley

Hyponatremia is a commonly observed complication that is related to hypoalbuminemia and portal hypertension in patients with advanced liver cirrhosis. Hyponatremia in patients with liver cirrhosis is mostly dilutional hyponatremia and is defined when the serum sodium concentration is below 130 meq/L. The risk of complications increases significantly in cirrhotic patients with hyponatremia, which includes spontaneous bacterial peritonitis, hepatorenal syndrome, and hepatic encephalopathy. In addition, hyponatremia is associated with increased morbidity and mortality in patients with cirrhosis, and is an important prognostic factor before and after liver transplantation. The conventional therapies of hyponatremia are albumin infusion, fluid restriction and loop diuretics, but these are frequently ineffective. This review investigates the pathophysiology and various therapeutic modalities, including selective vasopressin receptor antagonists, for the management of hyponatremia in patients with liver cirrhosis.
Antidiuretic Hormone Receptor Antagonists ; Fibrosis ; Hepatic Encephalopathy ; Hepatorenal Syndrome ; Humans ; Hypertension, Portal ; Hypoalbuminemia ; Hyponatremia* ; Liver Cirrhosis* ; Liver Transplantation ; Liver* ; Mortality ; Peritonitis ; Sodium ; Sodium Potassium Chloride Symporter Inhibitors

Arginine vasopressin (AVP), a neurohormone and hemodynamic factor implicated in the pathophysiology of hypertension and congestive heart failure, can also act as a growth-stimulating factor. Our previous work demonstrated that AVP is a mitogen for neonatal rat cardiac fibroblasts (CFs). In the present study, we extended our investigations to adult rat CFs to explore whether AVP could induce adult rat CF proliferation and, if so, to identify the mechanism involved. Adult rat CFs were isolated, cultured and subjected to AVP treatment. DNA synthesis and cell cycle distribution were analyzed by [(3)H]-thymidine incorporation and flow cytometry. Cellular extracellular signal-regulated kinase 1/2 (ERK1/2) activity was measured by in vitro kinase assay using myelin basic protein (MBP) as a substrate. Protein expressions of total- and phospho-ERK1/2, p27(Kip1), cyclins D1, A, E were assessed by Western blot. The results showed that AVP stimulated DNA synthesis in adult rat CFs, and the effect was abolished by a V1 receptor antagonist, d(CH(2))(5)[Tyr(2)(Me), Arg(8)]-vasopressin (0.1 μmol/L), but not by a V2 receptor antagonist, desglycinamide-[d(CH(2))(5), D-Ile(2), Ile(4), Arg8]-vasopressin (0.1 μmol/L). AVP induced an activation of ERK1/2, which could be mimicked by the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA, 30 nmol/L, 5 min), but abolished by depletion of PKC via chronic PMA incubation (2.5 μmol/L, 24 h). In addition, AVP down-regulated protein expression of p27(Kip1), increased protein expressions of cyclins D1, A and E, and induced cell cycle progression from G(0)/G(1) into S stage. Inhibition of ERK1/2 activation by PD98059 (30 μmol/L) abolished the effect of AVP on DNA synthesis, protein expressions of p27(Kip1), cyclins D1, A and E as well as cell cycle progression. These results suggest that AVP is also a growth factor for adult rat CFs. The mitogenic effect of AVP is mediated via V1 receptors and PKC-ERK1/2 pathway. Moreover, AVP modulates the expressions of cell cycle regulatory proteins p27(Kip1) and cyclins D1, A and E, which lie downstream of ERK1/2 activation, and induces cell cycle progression in adult rat CFs.
Animals ; Antidiuretic Hormone Receptor Antagonists ; pharmacology ; Arginine Vasopressin ; pharmacology ; Cell Cycle ; Cell Cycle Proteins ; metabolism ; Cell Proliferation ; Fibroblasts ; cytology ; drug effects ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Myocardium ; cytology ; Phosphorylation ; Protein Kinase C ; metabolism ; Rats ; Signal Transduction ; Tetradecanoylphorbol Acetate ; pharmacology

OBJECTIVETo evaluate the efficacy and safety of tolvaptan on treating congestive heart failure patients with hyponatremia.

METHODSThis randomized double-blind placebo-controlled multicenter trial enrolled 65 patients with congestive heart failure and hyponatremia. On top of standard therapy, patients were randomized to receive either tolvaptan 15 - 60 mg daily or placebo according to the serum sodium concentration. The primary end points were the change of average daily serum sodium concentration from baseline to day 4 and to day 7 respectively. Patients' weight, urine volume, sign of heart failure, heart function, blood pressure, heart rate, and all adverse events were observed.

RESULTSThe daily serum sodium concentration increase was significantly higher in tolvaptan group than in placebo group during the first 4 days [(5.6 ± 3.5) mmol/L vs. (2.5 ± 3.4) mmol/L, P < 0.05] and 7 days [(5.9 ± 3.5) mmol/L vs. (2.8 ± 3.3) mmol/L, P < 0.05]. Moreover, urine volume increase and body weight decrease were more significant in tolvaptan group than in placebo group (all P < 0.05). The change of sign of heart failure, heart function, blood pressure and heart rate was similar between two groups (P > 0.05). There were more drug related adverse events of thirst (11.4%) and hypernatremia (5.7%) in Tolvaptan group. One patient in tolvaptan group developed agranulocytosis during therapy period and recovered post therapy.

CONCLUSIONSTolvaptan could effectively increase serum sodium concentration, urine volume, and improve liquid balance in heart failure patients with hyponatremia. Tolvaptan related serious adverse event was low and could be well tolerated by patients tested in this cohort.

Aged ; Antidiuretic Hormone Receptor Antagonists ; adverse effects ; therapeutic use ; Benzazepines ; adverse effects ; therapeutic use ; Blood Pressure ; Body Weight ; Double-Blind Method ; Heart Failure ; complications ; drug therapy ; Humans ; Hyponatremia ; complications ; Sodium ; blood