Functional status of beta-2-adrenoceptor in isolated membranes of mature erythrocytes from patients with cirrhosis and oesophageal varices

Treatment with non-selective beta-blockers affects the systemic inflammatory response to bacterial DNA in patients with cirrhosis

BACKGROUND & AIMS

The use of non-selective beta-blockers has been associated with lower rates of infection and reduced infection-associated morbidity in patients with cirrhosis. However, it is unknown if these drugs modify the systemic inflammatory response to circulating bacterial DNA.

METHODS

Sixty-three patients with cirrhosis were included during an episode of decompensation by ascites. Thirty of those patients were on beta-blockers. Blood samples were obtained after each patient had been in the supine position for at least 30 minutes in a quiet atmosphere. Bacterial DNA, serum cytokines, nitric oxide, and LPS were determined. Phagocytic and oxidative burst activities were determined in polymorphonuclear cells from the patients.

RESULTS

The detection rate of bacterial DNA in the blood was the same (33%) for patients not treated and treated with non-selective beta-blockers. Patients naive to non-selective beta-blockers showed significantly higher serum levels of IL6, IFN-gamma and IL10 in response to the presence of bacterial DNA. Patients treated with non-selective beta-blockers showed higher basal inflammatory activity that did not change with the presence of bacterial DNA. Monocytes and granulocytes from patients treated with non-selective beta-blockers showed a significantly increased phagocytic capacity in the presence of bacterial DNA.

CONCLUSIONS

In patients with cirrhosis, chronic treatment with beta-blockers is associated with a higher unstimulated production of serum cytokines and an increased phagocytic activity in the presence of bacterial DNA.

β2‑adrenergic receptor functionality and genotype in two different models of chronic inflammatory disease: Liver cirrhosis and osteoarthritis

The present study was designed to investigate the functional status of β2 adrenoceptors (β2AR) in two models of chronic inflammatory disease: liver cirrhosis (LC) and osteoarthritis (OA). The β2AR gene contains three single nucleotide polymorphisms at amino acid positions 16, 27 and 164. The aim of the present study was to investigate the potential influence of lymphocyte β2AR receptor functionality and genotype in LC and OA patients. Blood samples from cirrhotic patients (n=52, hepatic venous pressure gradient 13±4 mmHg, CHILD 7±2 and MELD 11±4 scores), OA patients (n=30, 84% Kellgren‑Lawrence severity 4 grade, 14% knee replacement joint) and healthy volunteers as control group (n=26) were analyzed. Peripheral blood mononuclear cells (PBMC) were isolated from whole blood and basal and isoproterenol induced adenylate cyclase activity (isoproterenol stimulus from 10‑9 to 10‑4 mM), and β2AR allelic variants (rs1042713, rs1042714, rs1800888) were determined. β2AR functionality was decreased in the two different models of chronic inflammatory disease studied, OA (50% vs. control) and LC (85% vs. control). In these patients, the strength of the β2AR response to adrenergic stimulation was very limited. Adrenergic modulation of PBMC function through the β2AR stimulus is decreased in chronic inflammatory processes including LC and OA, suggesting that the adrenergic system may be important in the development of these processes.

Effects of dexmedetomidine on the deformability of erythrocytes in vitro and in anesthesia

The current study aimed to evaluate the impact of clinically relevant concentrations of dexmedetomidine on the deformability of erythrocytes in vitro and the effects of dexmedetomidine on the deformability of erythrocytes in patients undergoing laparoscopic cholecystectomy. Erythrocyte suspensions of different concentrations were divided into six groups: Control (group C); low, medium and high concentrations of dexmedetomidine (groups DL, DM and DH, respectively); yohimbine alone (group Y) and yohimbine mixed with dexmedetomidine (group YD). The suspensions were incubated in a thermostatic shaking incubator (50 rpm, 37°C) for 60 min. The nitric oxide (NO) concentrations and endothelial nitric oxide synthase (eNOS) activities of red blood cells and the erythrocyte deformability index (EI) were then measured. Patients (n=40) scheduled for laparoscopic cholecystectomy were randomly divided into a dexmedetomidine group (group A) and a control group (group B). The induction and maintenance of anesthesia in the two groups was identical. The EI and hematocrit (Hct) were assayed prior to anesthesia (T₀) and following the surgery (T₁). In the in vitro assay, the EI, the activity of eNOS and the NO concentration of the erythrocytes were significantly higher in groups DL, DM, DH and YD than in group C (P<0.05). In addition, the EI, the eNOS activity and NO concentration of the erythrocytes were higher in group DM than in group YD (P<0.05). In the patients, the EI value at T₁ (0.90±0.04) was higher than at T₀ (0.81±0.06) in group B (P<0.05). No statistically significant difference between the EI values at T₀ and T₁ was identified in group A (P>0.05). Dexmedetomidine treatment is able to improve the deformability of erythrocytes in vitro and in anesthesia. The improvement of erythrocyte deformability by dexmedetomidine may be partially associated with adrenergic receptors through activation of eNOS to enhance the concentration of NO in red blood cells.

Zolmitriptan: a novel portal hypotensive agent which synergizes with propranolol in lowering portal pressure

OBJECTIVE

Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol.

METHODS

ZOLMITRIPTAN, PROPRANOLOL OR BOTH WERE TESTED IN TWO RAT MODELS OF PORTAL HYPERTENSION: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan.

RESULTS

In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of β2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by β2-agonists.

CONCLUSION

Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combination therapy deserves consideration for patients with portal hypertension failing to respond to non-selective beta-blockers.