Effects of bupivacaine on human erythrocytes submitted to stress and evidence for an interaction between bupivacaine and flumazenil

Protective effect of desloratadine against oxidative stress in human erythrocytes in vitro

Desloratadine (DCL) is a non-sedating antihistamine approved for the treatment of allergic rhinitis or chronic idiopathic urticaria. The objective of this study was to evaluate the potential protective effect of DCL against oxidative stress in human erythrocytes in vitro. Human erythrocytes were oxidized by a water-soluble radical generators-2,2' azobis (2-amidinopropane) hydrochloride (AAPH; 20, 50mM) or tert-butyl hydroperoxide (TBHP; 0.5mM) and the protective effects of DCL (2, 5, 7, 10 and 26μM) on selected oxidative stress markers were investigated. Erythrocytes were divided into aliquots. The first aliquot was incubated for 2h at 37°C with AAPH or TBHP. The other test aliquots were preincubated with selected concentrations of DCL for 30min and followed by AAPH or TBHP incubation for 2h. Malondialdehyde (MDA) content, catalase (CAT) and superoxide dismutase (SOD) activities, as well as hemolysis percentage (H) were measured in all erythrocyte samples. The influence of solvent (0.5% ethanol) on the parameters studied was also checked. Pretreatment with DCL (7, 10, 26μM) could prevent TBHP-induced increase in MDA formation in a concentration-dependent manner. DCL has no influence on CAT activity and it significantly enhanced SOD activity compared to AAPH treatment samples at 7, 10, 26μM. DCL (26μM) also reduced the hemolytic effect on erythrocytes when compared to the erythrocytes exposed to oxidants only. These results suggest a beneficial effect of DCL as an antioxidant, which might be an additional explanation of its therapeutic action.

Effects of an oxidative stress on human hemoglobin: a multiwavelength visible spectrometry study

This study was carried out to investigate hemoglobin behavior and the role of cell membrane during oxidative stress of human red blood cells induced by a water-soluble radical initiator, 2,2'-azobis(amidino-propane) hydrochloride (AAPH) and compare the observed data to the one obtained with purified human haemoglobin solution. The different forms of hemoglobin were identified and quantified by multiwavelength visible spectrometry using multiple linear regression analysis. Hemolysis was quantified by the Drabkin method. Oxidative stress on purified hemoglobin solutions induced an early formation of Hb(+). In intact erythrocytes, no modified form of haemoglobin was found. Only the hemoglobin released by hemolysis in the extracellular medium was notified in the same way as purified haemoglobin. Thus, the cell membrane appears to protect intraerythrocytic hemoglobin toward an extracellular oxidative stress. Oxidative stress-induced by hemolysis does not seem to be due to changes in intraerythrocytic hemoglobin forms.

Lidocaine has better antioxidant potential than ropivacaine and bupivacaine: in vitro comparison in a model of human erythrocytes submitted to an oxidative stress

BACKGROUND

Local anesthetic agents may exert antioxidant properties in various models. The aim of this work was to compare the antioxidant properties of lidocaine, bupivacaine and ropivacaine using an in vitro model of human erythrocytes submitted to an oxidative stress.

METHODS

Blood was obtained from healthy volunteers. After separation, erythrocytes were suspended in phosphate buffer. Oxidative stress was induced by incubation with 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH). (1) Effects of four different concentrations (50, 100, 300 and 600 microg ml(-1)) of lidocaine, bupivacaine and ropivacaine were studied in absence or presence of AAPH (20 mM). Potassium efflux was assessed by flame photometry. (2) Effects of 50 and 600 microg ml(-1) of lidocaine, bupivacaine and ropivacaine on AAPH (50 mM) induced hemolysis were also studied. (3) The oxygen radical absorbing capacity of lidocaine, bupivacaine and ropivacaine at the four concentrations was evaluated by the analysis of the allophycocyanin fluorescence.

RESULTS

In absence of AAPH, neither extracellular potassium nor hemolysis was noted. AAPH (20 mM) induced a significant increase in extracellular potassium that was reduced by all local anesthetic agents, with greater effects for lidocaine. AAPH-induced hemolysis was significantly decreased by all the local anesthetic agents at higher concentration, but only by lidocaine at 50 microg ml(-1). Finally, none of the local anesthetic agents modified the allophycocyanin fluorescence.

CONCLUSION

In this model, lidocaine was proved more effective than bupivacaine and ropivacaine in protecting human erythrocytes submitted to an oxidative challenge. This was not due to a free radical scavenging effect.