Different damaging effects of volatile anaesthetics alone or in combination with 1 and 2 Gy gamma-irradiation in vivo on mouse liver DNA: a preliminary study.

As the number of radiotherapy and radiology diagnostic procedures increases from year to year, so does the use of general volatile anaesthesia (VA). Although considered safe, VA exposure can cause different adverse effects and, in combination with ionising radiation (IR), can also cause synergistic effects. However, little is known about DNA damage incurred by this combination at doses applied in a single radiotherapy treatment. To learn more about it, we assessed DNA damage and repair response in the liver tissue of Swiss albino male mice following exposure to isoflurane (I), sevoflurane (S), or halothane (H) alone or in combination with 1 or 2 Gy irradiation using the comet assay. Samples were taken immediately (0 h) and 2, 6, and 24 h after exposure. Compared to control, the highest DNA damage was found in mice receiving halothane alone or in combination with 1 or 2 Gy IR treatments. Sevoflurane and isoflurane displayed protective effects against 1 Gy IR, while with 2 Gy IR the first adverse effects appeared at 24 h post-exposure. Although VA effects depend on liver metabolism, the detection of unrepaired DNA damage 24 h after combined exposure with 2 Gy IR indicates that we need to look further into the combined effects of VA and IR on genome stability and include a longer time frame than 24 h for single exposure as well as repeated exposure as a more realistic scenario in radiotherapy treatment.

Scavenger receptor a is a major homeostatic regulator that restrains drug-induced liver injury.

BACKGROUND AND AIM: Drug-induced liver injury occurs frequently and can be life threatening. Although drug-induced liver injury is mainly caused by the direct drug cytotoxicity, increasing evidence suggests that the interplay between hepatocytes and immune cells can define this pathogenic process. Here, we interrogate the role of the pattern recognition scavenger receptor A (SRA) for regulating hepatic inflammation and drug-induced liver injury. APPROACH AND RESULTS: Using acetaminophen (APAP) or halothane-induced liver injury models, we showed that SRA loss renders mice highly susceptible to drug hepatotoxicity, indicated by the increased mortality and liver pathology. Mechanistic studies revealed that APAP-induced liver injury exaggerated in the absence of SRA was associated with the decreased anti-inflammatory and prosurvival cytokine IL-10 concomitant with excessive hepatic inflammation. The similar correlation between SRA and IL-10 expression was also seen in human following APAP uptake. Bone marrow reconstitution and liposomal clodronate depletion studies established that the hepatoprotective activity of SRA mostly resized in the immune sentinel KCs. Furthermore, SRA-facilitated IL-10 production by KCs in response to injured hepatocytes mitigated activation of the Jun N-terminal kinase-mediated signaling pathway in hepatocytes. In addition, supplemental use of IL-10 with N -acetylcysteine, only approved treatment of APAP overdose, conferred mice improved protection from APAP-induced liver injury. CONCLUSION: We identify a novel hepatocyte-extrinsic pathway governed by the immune receptor SRA that maintains liver homeostasis upon drug insult. Giving that drug (ie, APAP) overdose is the leading cause of acute liver failure, targeting this hepatoprotective SRA-IL-10 axis may provide new opportunities to optimize the current management of drug-induced liver injury.

Kidney cell DNA damage caused by combined exposure to volatile anaesthetics and 1 Gy or 2 Gy radiotherapy dose in vivo.

Patient immobilisation with volatile anaesthetics (VA) during radiotherapy is sometimes unavoidable. Although it is known that both VAs and ionising radiation can have nephrotoxic effects, there are no studies of their combined effects on DNA damage. The aim of this in vivo study was to address this gap by investigating whether 48 groups of healthy Swiss albino mice (totalling 240) would differ in kidney cell DNA damage response (alkaline comet assay) to isoflurane, sevoflurane, or halothane anaesthesia and exposure to 1 Gy or 2 Gy of ionising radiation. We took kidney cortex samples after 0, 2, 6, and 24 h of exposure and measured comet parameters: tail length and tail intensity. To quantify the efficiency of the cells to repair and re-join DNA strand breaks, we also calculated cellular DNA repair index. Exposure to either VA alone increased DNA damage, which was similar between sevoflurane and isoflurane, and the highest with halothane. In combined exposure (VA and irradiation with 1 Gy) DNA damage remained at similar levels for all time points or was even lower than damage caused by radiation alone. Halothane again demonstrated the highest damage. In combined exposure with irradiation of 2 Gy sevoflurane significantly elevated tail intensity over the first three time points, which decreased and was even lower on hour 24 than in samples exposed to the corresponding radiation dose alone. This study confirmed that volatile anaesthetics are capable of damaging DNA, while combined VA and 1 Gy or 2 Gy treatment did not have a synergistic damaging effect on DNA. Further studies on the mechanisms of action are needed to determine the extent of damage in kidney cells after longer periods of observation and how efficiently the cells can recover from exposure to single and multiple doses of volatile anaesthetics and radiotherapy.

Pharmacological evidence for the involvement of ryanodine receptors in halothane-induced liver injury in mice.

Drug-induced liver injury (DILI) is a major safety concern in drug development. Halothane (HAL), an inhaled anesthetic, induces severe and idiosyncratic liver injury. Ryanodine receptors (RyR) are major intracellular calcium release channels found on the plasma membrane of the endoplasmic reticulum (ER). It has been reported that disordered hepatic calcium homeostasis is a feature of HAL-induced liver injury (HILI) in guinea pigs. However, there are no reports on whether RyR could mediate the pathogenesis of HILI. The aim of the present study was to investigate the effect of RyR on HILI. Ryanodine (RYA, RyR agonist, 50 µg/kg, i.p.) was administered to BALB/c female mice 1 h before HAL administration (15 mmol/kg, i.p.), which significantly elevated plasma transaminase levels and induced severe hepatic inflammation and necrosis. In contrast, dantrolene sodium (DAN, RyR antagonist) treatment significantly suppressed HILI in a dose- and time-dependent manner and alleviated liver damage. The number of infiltrated neutrophils in the liver were higher in the group treated with HAL + RYA than in the group treated with HAL alone, while DAN treatment decreased neutrophil infiltration in HILI. The hepatic mRNA levels of proinflammatory cytokines; chemokines; and factors related to danger signals, neutrophils, oxidative and ER stress, pro-apoptosis, and RyR were significantly increased with RYA pretreatment, whereas these levels were decreased with DAN treatment. These results suggest that RYA exacerbates HILI, and DAN exerts a protective effect against HILI. Hence, our study provides a novel insight regarding the effect of RyR in the mechanism underlying HILI.

Antioxidants protect calsequestrin-1 knockout mice from halothane- and heat-induced sudden death.

BACKGROUND: Mice lacking calsequestrin-1 (CASQ1-null), a Ca-binding protein that modulates the activity of Ca release in the skeletal muscle, exhibit lethal hypermetabolic episodes that resemble malignant hyperthermia in humans when exposed to halothane or heat stress. METHODS: Because oxidative species may play a critical role in malignant hyperthermia crises, we treated CASQ1-null mice with two antioxidants, N-acetylcysteine (NAC, Sigma-Aldrich, Italy; provided ad libitum in drinking water) and (±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox, Sigma-Aldrich; administered by intraperitoneal injection), before exposure to halothane (2%, 1 h) or heat (41°C, 1 h). RESULTS: NAC and Trolox significantly protected CASQ1-null mice from lethal episodes, with mortality being 79% (n = 14), 25% (n = 16), and 20% (n = 5) during halothane exposure and 86% (n = 21), 29% (n = 21), and 33% (n = 6) during heat stress in untreated, NAC-treated, and Trolox-treated mice, respectively. During heat challenge, an increase in core temperature in CASQ1-null mice (42.3° ± 0.1°C, n=10) was significantly reduced by both NAC and Trolox (40.6° ± 0.3°C, n = 6 and 40.5° ± 0.2°C, n = 6). NAC treatment of CASQ1-null muscles/mice normalized caffeine sensitivity during in vitro contracture tests, Ca transients in single fibers, and significantly reduced the percentage of fibers undergoing rhabdomyolysis (37.6 ± 2.5%, 38/101 fibers in 3 mice; 11.6 ± 1.1%, 21/186 fibers in 5 mice). The protective effect of antioxidant treatment likely resulted from mitigation of oxidative stress, because NAC reduced mitochondrial superoxide production, superoxide dismutase type-1 expression, and 3-nitrotyrosine expression, and increased both reduced glutathione and reduced glutathione/oxidized glutathione ratio. CONCLUSION: These studies provide a deeper understanding of the mechanisms that underlie hyperthermic crises in CASQ1-deficient muscle and demonstrate that antioxidant pretreatment may prevent them.

Drug-induced allergic hepatitis develops in mice when myeloid-derived suppressor cells are depleted prior to halothane treatment.

UNLABELLED: Clinical evidence suggests that many cases of serious idiosyncratic drug-induced liver injury are mediated by the adaptive immune system in response to hepatic drug-protein adducts, also referred to as "drug-induced allergic hepatitis"; but detailed mechanistic proof has remained elusive due to the lack of animal models. We have hypothesized that drug-induced allergic hepatitis is as rare in animals as it is in humans due at least in part to the tolerogenic nature of the liver. We provide evidence that immune tolerance can be overcome in a murine model of halothane-induced liver injury initiated by trifluoroacetylated protein adducts of halothane formed in the liver. Twenty-four hours after female Balb/cJ mice were initially treated with halothane, perivenous necrosis and an infiltration of CD11b(+) Gr-1(high) cells were observed in the liver. Further study revealed a subpopulation of myeloid-derived suppressor cells within the CD11b(+) Gr-1(high) cell fraction that inhibited the proliferation of both CD4(+) and CD8(+) T cells. When CD11b(+) Gr-1(high) cells were depleted from the liver with Gr-1 antibody treatment, enhanced liver injury was observed at 9 days after halothane rechallenge. Toxicity was associated with increased serum levels of interleukin-4 and immunoglobulins G1 and E directed against hepatic trifluoroacetylated protein adducts, as well as increased hepatic infiltration of eosinophils and CD4(+) T cells, all features of an allergic reaction. When hepatic CD4(+) T cells were depleted 5 days after halothane rechallenge, trifluoroacetylated protein adduct-specific serum immunoglobulin and hepatotoxicity were reduced. CONCLUSION: Our data provide a rational approach for developing animal models of drug-induced allergic hepatitis mediated by the adaptive immune system and suggest that impaired liver tolerance may predispose patients to this disease.

The effect of succinylcholine on malignant hyperthermia events in susceptible swine.

BACKGROUND: While the impact of volatile anaesthetics to induce malignant hyperthermia (MH) is abundantly clear, the role of succinylcholine still remains controversial. To evaluate the influence of succinylcholine on porcine MH events, the authors investigated the hemodynamic and metabolic responses in MH susceptible (MHS) and non-susceptible (MHN) swine following either succinylcholine or halothane application alone or a combination of both substances. METHODS: With approval of the local animal care committee 27 MHS and 30 MHN pigs were anaesthetized and mechanically ventilated. Fiberoptic probes for continuous PCO2 measurement were inserted into the femoral vein and the triceps muscle. Group A received succinylcholine 4 mg/kg, group B incremental doses of halothane (0.5, 1.0 vol%) and group C succinylcholine and halothane simultaneously. Vital signs were recorded continuously. RESULTS: Prior to drug application measured values did not differ between MHS and MHN. While MHN pigs did not show relevant alterations, succinylcholine, halothane and the combination of both lead to significant hemodynamic and metabolic changes in MHS swine. CONCLUSIONS: Hemodynamic and metabolic alterations following succinylcholine were similar to halothane in MHS pigs. The combination of both pharmacological agents potentiated the observed effects. According to these results succinylcholine acted as an independent and supportive factor during onset of an MH episode.

Determination of DNA damage after exposure to inhalation anesthetics in human peripheral lymphocytes and sperm cells in vitro by comet assay.

In this study, genotoxic activities of four halogenated anesthetics (halothane, isoflurane, sevoflurane and desflurane) were investigated in human peripheral blood lymphocytes (PBLs) and sperm cells in vitro by alkaline comet assay. For this purpose, sperm or lymphocyte suspension was exposed to different concentrations (0.1 mM, 1 mM, 10 mM and 100 mM) of anesthetic agents and 1% dimethyl sulfoxide (DMSO) or phosphate-buffered saline (PBS) as controls. The DNA strand breaks as well as alkali-labile sites were measured as percentage tail intensity with comet assay. The results of this study demonstrate that all analyzed drugs were capable of inducing DNA damage on PBLs in a dose-dependent manner in vitro. However, the results in sperm cells were slightly different since we did not observe any genotoxic effect for desflurane in any of the exposure doses, and the genotoxic effect of halothane was not dose dependent. This experimental study points out to the presence of DNA damage after exposure to halogenated anesthetics in both PBLs and sperm cells, although this effect seems to be higher in PBLs.

The in vivo genotoxicity of cisplatin, isoflurane and halothane evaluated by alkaline comet assay in Swiss albino mice.

The aim of this study was to evaluate the genotoxicity of repeated exposure to isoflurane or halothane and compare it with the genotoxicity of repeated exposure to cisplatin. We also determined the genotoxicity of combined treatment with inhalation anaesthetics and cisplatin on peripheral blood leucocytes (PBL), brain, liver and kidney cells of mice. The mice were divided into six groups as follows: control, cisplatin, isoflurane, cisplatin-isoflurane, halothane and cisplatin-halothane, and were exposed respectively for three consecutive days. The mice were treated with cisplatin or exposed to inhalation anaesthetic; the combined groups were exposed to inhalation anaesthetic after treatment with cisplatin. The alkaline comet assay was performed. All drugs had a strong genotoxicity (P<0.05 vs. control group) in all of the observed cells. Isoflurane caused stronger DNA damage on the PBL and kidney cells, in contrast to halothane, which had stronger genotoxicity on brain and liver cells. The combination of cisplatin and isoflurane induced lower genotoxicity on PBL than isoflurane alone (P<0.05). Halothane had the strongest effect on brain cells, but in the combined treatment with cisplatin, the effect decreased to the level of cisplatin alone. Halothane also induced the strongest DNA damage of the liver cells, while the combination with cisplatin increased its genotoxicity even more. The genotoxicity of cisplatin and isoflurane on kidney cells were nearly at the same level, but halothane caused a significantly lower effect. The combinations of inhalation anaesthetics with cisplatin had stronger effects on kidney cells than inhalation anaesthetics alone. The observed drugs and their combinations induced strong genotoxicity on all of the mentioned cells.

Natural killer cells mediate severe liver injury in a murine model of halothane hepatitis.

Severe halothane (HAL)-induced hepatotoxicity occurs in one in 6000-30,000 patients by an unknown mechanism. Female sex is a risk factor in humans and rodents. We tested the hypothesis that a sex difference in natural killer (NK) cell activity contributes to HAL-induced liver injury. HAL (15 mmol/kg, ip) treatment resulted in severe liver injury by 12 h in female, wild-type BALB/cJ mice, and the magnitude of liver injury varied with stage of the estrous cycle. Ovariectomized (OVX) mice developed only mild liver injury. Plasma interferon-gamma (IFN-γ) was elevated 10-fold in HAL-treated females compared with similarly treated male mice or with OVX female mice. IFN-γ knockout mice were resistant to severe HAL-induced liver injury. The deactivation of NK cells with anti-asialo GM1 treatment attenuated liver injury and the increase in plasma IFN-γ compared with immunoglobulin G-treated control mice. Mice with a mutated form of perforin, a protein involved in granule-mediated cytotoxicity, were protected from severe liver injury. Furthermore, HAL increased the activity of NK cells in vivo, as indicated by increased surface expression of CD69, an early activation marker. In response to HAL, NK cell receptor ligands on the surface of hepatocytes were expressed in a manner that can activate NK cells. These results confirm the sexual dimorphic hepatotoxic response to HAL in mice and suggest that IFN-γ and NK cells have essential roles in the development of severe HAL-induced hepatotoxicity.

Involvement of natural killer T cells in halothane-induced liver injury in mice.

Drug-induced liver injury (DILI) causes significant patient morbidity and mortality, and is the most common reason for drug withdrawals. It is imperative to gain a thorough understanding of the underlying mechanisms of DILI to effectively predict and prevent these reactions. We have recently developed a murine model of halothane-induced liver injury (HILI). The aim of the present study was to investigate the role of hepatic natural killer T (NKT) cells in the pathogenesis of HILI. The degrees of HILI were compared between WT and CD1d(-/-) mice, which are deficient in NKT cells. The data revealed that CD1d(-/-) mice were resistant in developing HILI. This resistance appeared to be a direct result of NKT cell depletion rather than an indirect one due to the absence of cross-talk between NKT cells and other hepatic innate immune cells. Compared with WT mice, CD1d(-/-) mice exhibited a significantly lower number of hepatic infiltrating neutrophils upon halothane challenge (470,000+/-100,000/liver in WT vs. 120,000+/-31,500/liver in CD1d(-/-) mice). This result in conjunction with our previous finding of an indispensable role of neutrophils in HILI strongly suggests that NKT cells play a critical role in regulating neutrophil recruitment, thereby contributing to the development of HILI. Collectively, the current study and published reports indicate that this murine model of HILI provides an experimental system for the investigation of the underlying mechanisms of DILI. In addition, this model may yield the discovery of susceptibility factors that may control the development of liver injury in patients treated with halothane and potentially other drugs.

Generation of T cell responses targeting the reactive metabolite of halothane in mice.

Immune-mediated adverse drug reactions (IADRs) represent a significant problem in clinical practice and drug development. Studies of the underlying mechanisms of IADRs have been hampered by the lack of animal models. Halothane causes severe allergic hepatitis with clinical features consistent with an IADR. Our ultimate goal is to develop a mouse model of halothane hepatitis. Evidence suggests that adaptive immune responses targeting liver protein adducts of the reactive metabolite (trifluoroacetyl (TFA)) play an important role in the pathogenesis. The present study demonstrated that the combination of an anti-CD40 antibody (Ab) and a Toll-like receptor (TLR) agonist served as a potent adjuvant in generating TFA-specific T cell responses in mice. Both CD4(+) and CD8(+) subsets of T cells were activated and the TFA-specific responses were detected not only in the spleen but also in the liver of mice immunized with mouse serum albumin adducts of TFA (TFA-MSA) plus the combined CD40/TLR agonist. Whereas all three TLR agonists examined were effective in eliciting TFA-specific immune responses in BALB/cByJ mice, only polyI:C was effective in DBA/1 mice and none of the TLR agonists could aid the generation of TFA-specific T cells in C57BL/6J mice. This result, combined with our previous finding that BALB/cByJ mice were the most susceptible to halothane-induced acute liver injury, provides the basis for employing this strain in future studies. Collectively, our data demonstrated the successful completion of a crucial first step in the development of a murine model of halothane hepatitis.

Halothane-induced liver injury is mediated by interleukin-17 in mice.

Drug-induced liver injury is a major problem in drug development and clinical drug therapy. In most cases the mechanisms are still unknown, thus, it is difficult to predict or prevent these reactions. It has been known that halothane, an inhaled anesthetic, induces liver injury. To investigate the mechanisms of halothane-induced liver injury, we used a recently established mouse model of liver injury. The expression of transcription factors and cytokines specific for Th1 and Th2 (helper T cells), respectively, were compared between BALB/c and C57BL/6 mice. The mRNA expression ratios of mouse T-bet(a Th1-specific transcription factor)/GATA-binding protein (GATA-3, a Th2-specific transcription factor) and interferon gamma/interleukin (IL)-10 were lower in BALB/c mice compared with C57BL/6 mice, suggesting that a typical Th1 or Th2-dominant response could not be distinguished in halothane-induced liver injury. We observed increases of the plasma IL-17 level and hepatic macrophage inflammatory protein 2 expression in halothane-administrated BALB/c mice, as well as neutrophil infiltration. Neutralization of IL-17 suppressed the hepatotoxic effect of halothane. Administration of recombinant IL-17 (1 microg per mouse, single ip) to the halothane-treated mice resulted in a remarkable increase of alanine and aspartate aminotransferases. In conclusion, we demonstrated that IL-17 is involved in the halothane-induced liver injury.

Effect of polyI:C cotreatment on halothane-induced liver injury in mice.

UNLABELLED: Drug-induced liver injury (DILI) is a challenging problem in drug development and clinical practice. Patient susceptibility to DILI is multifactorial, making these reactions difficult to predict and prevent. Clinical observations have suggested that concurrent bacterial and viral infections represent an important risk factor in determining patient susceptibility to developing adverse drug reactions, although the underlying mechanism is not clear. In the present study, we employed the viral RNA mimetic (polyinosinic-polycytidylic acid [polyI:C]) to emulate viral infection and examined its effect on halothane-induced liver injury. Although pretreatment of mice with polyI:C attenuated halothane hepatotoxicity due to its inhibitory effect on halothane metabolism, posttreatment significantly exacerbated liver injury with hepatocellular apoptosis being significantly higher than that in mice treated with polyI:C alone or halothane alone. The pan-caspase inhibitor z-VAD-fmk suppressed liver injury induced by polyI:C/posthalothane cotreatment, suggesting that the increased hepatocyte apoptosis contributes to the exacerbation of liver injury. Posttreatment with polyI:C also caused activation of hepatic Kupffer cells (KCs) and natural killer (NK) cells and upregulated multiple proapoptotic factors, including tumor necrosis factor-alpha (TNF-alpha), NK receptor group 2, member D (NKG2D), and Fas ligand (FasL). These factors may play important roles in mediating polyI:C-induced hepatocyte apoptosis. CONCLUSION: This is the first study to provide evidence that concurrent viral infection can inhibit cytochrome (CYP)450 activities and activate the hepatic innate immune system to proapoptotic factors. DILI may be attenuated or exacerbated by pathogens depending on the time of infection.

Interleukin 10 deficiency exacerbates halothane induced liver injury by increasing interleukin 8 expression and neutrophil infiltration.

The prediction and prevention of drug-induced liver injury (DILI) have been hindered by limited knowledge of the underlying mechanisms, in part the result of a lack of animal models. Using a newly established DILI model induced by halothane, we found increased liver damage susceptibility in interleukin 10 (IL-10) knockout (KO) mice. Extensive neutrophil infiltration and chemoattractant factor interleukin 8 (IL-8) expression in IL-10 KO mice were observed after halothane administration. The elevation of IL-8 expression was NF-kappaB- and P38 MAPK-dependent. In addition, increased signal transducer and activator of transcription factors (STAT) 1 and STAT3 were observed in halothane treated IL-10 KO mice. Exogenous IL-10 treatment protected susceptible mice from halothane induced liver injury (HILI). In conclusion, IL-10 deficiency increases susceptibility to HILI and increased IL-8 expression as well as neutrophil infiltration may be responsible for this phenomenon.

The role of the antioxidants lycopene and vitamin E in the prevention of halothane-induced hepatotoxicity.

The aim of this study was to examine the effects of lycopene and vitamin E on halothane-induced hepatotoxicity. Thirty-five male albino Wistar rats were studied. The control group (group C) did not receive any treatment. Rats in group H were exposed to 1.5% halothane (in 50% oxygen/50% air) for 2 h on days 10 and 13. Group L received 25 mg/kg/day lycopene, group E received 100 IU/kg/day vitamin E and group LE received lycopene and vitamin E for 13 days. Similar to group H, groups L, E and LE were exposed to halothane. Total antioxidant capacity (TAC), total oxidant level (TOL) and sulfhydryl=thiol groups (SH) were measured. Histopathological examinations were carried out using light microscopy, and histopathological findings were graded on a scale of 0-6. There were no significant differences among the groups in TAC, TOL and SH values (P > 0.05). Liver injury was observed in the four treatment groups; the mean degree of damage was more severe in group H compared to groups E, L and LE: 2.14 +/- 0.37, 1.50 +/- 0.54, 0.85 +/- 0.69 and 0.83 +/- 0.75, respectively. This study found that both lycopene and vitamin E reduce halothane-induced hepatotoxicity, although the effect of vitamin E was not statistically significant.

Isoflurane exacerbates electrically evoked seizures in amygdala-kindled rats during recovery.

Neuroexcitatory effects of isoflurane during or following anesthesia are controversial, particularly in epileptic patients. In contrast, halothane is generally considered to be highly anticonvulsant. Kindling is an animal model of epilepsy suitable for studying the effects of anesthetic agents on the epileptic brain. Fully kindled, Sprague-Dawley rats were either untreated or received a 5 min exposure to isoflurane or halothane 30 min prior to a seizure and compared to seizures in the absence of prior anesthesia. Afterdischarge duration was assessed via electroencephalographs recorded from electrodes implanted in the basolateral amygdala and behavioral seizure stereotypy (stages I-V) was simultaneously recorded and analyzed using digital video for all seizures. Total seizure duration and clonus duration were significantly (P<0.05) increased 30 min after isoflurane but not halothane exposure relative to pre-treatment control. These results are the first to demonstrate that isoflurane exacerbates electrically evoked secondarily generalized seizures in fully kindled animals during recovery. These results also show that the kindling paradigm is useful for evaluating the mechanism of anesthetic agents that may be proconvulsant in epileptic subjects.

Halothane-induced alterations in cellular structure and proliferation of A549 cells.

Genotoxicity, cytotoxicity or teratogenicity are among the well-known detrimental effects of the volatile anaesthetics. The aim of the present work was to study the structural changes, proliferative activity and the possibility of alveolar A549 cells to recover after in vitro exposure to halothane at 1.5 and 2.1mM concentrations. Our data indicated significant reduction of viability, suppression of mitotic activity more than 60%, and that these alterations were accompanied by disturbances of nuclear and nucleolar structures. The most prominent negative effect was the destruction of the lamellar bodies, the main storage organelles of pulmonary surfactant, substantial for the lung physiology. In conclusion, halothane applied at clinically relevant concentrations exerts genotoxic and cytotoxic effect on the alveolar cells in vitro, most likely as a consequence of stress-induced apoptosis, thus modulating the respiratory function.