Effect of halothane on lung carcinoma cells A 549

Distinct pathophysiological characteristics in developing muscle from patients susceptible to malignant hyperthermia

BACKGROUND

Most patients with malignant hyperthermia susceptibility diagnosed by the in vitro caffeine-halothane contracture test (CHCT) develop excessive force in response to halothane but not caffeine (halothane-hypersensitive). Hallmarks of halothane-hypersensitive patients include high incidence of musculoskeletal symptoms at rest and abnormal calcium events in muscle. By measuring sensitivity to halothane of myotubes and extending clinical observations and cell-level studies to a large group of patients, we reach new insights into the pathological mechanism of malignant hyperthermia susceptibility.

METHODS

Patients with malignant hyperthermia susceptibility were classified into subgroups HH and HS (positive to halothane only and positive to both caffeine and halothane). The effects on [Ca²⁺]_cyto of halothane concentrations between 0.5 and 3 % were measured in myotubes and compared with CHCT responses of muscle. A clinical index that summarises patient symptoms was determined for 67 patients, together with a calcium index summarising resting [Ca²⁺]_cyto and spontaneous and electrically evoked Ca²⁺ events in their primary myotubes.

RESULTS

Halothane-hypersensitive myotubes showed a higher response to halothane 0.5% than the caffeine-halothane hypersensitive myotubes (P<0.001), but a lower response to higher concentrations, comparable with that used in the CHCT (P=0.055). The HH group had a higher calcium index (P<0.001), but their clinical index was not significantly elevated vs the HS. Principal component analysis identified electrically evoked Ca²⁺ spikes and resting [Ca²⁺]_cyto as the strongest variables for separation of subgroups.

CONCLUSIONS

Enhanced sensitivity to depolarisation and to halothane appear to be the primary, mutually reinforcing and phenotype-defining defects of halothane-hypersensitive patients with malignant hyperthermia susceptibility.

The common anesthetic, sevoflurane, induces apoptosis in A549 lung alveolar epithelial cells

Lung alveolar epithelial cells are the first barrier exposed to volatile anesthetics, such as sevoflurane, prior to reaching the targeted neuronal cells. Previously, the effects of volatile anesthetics on lung surfactant were studied primarily with physicochemical models and there has been little experimental data from cell cultures. Therefore it was investigated whether sevoflurane induces apoptosis of A549 lung epithelial cells. A549 cells were exposed to sevoflurane via a calibrated vaporizer with a 2 l/min flow in a gas‑tight chamber at 37˚C. The concentration of sevoflurane in Dulbecco's modified Eagle's medium was detected with gas chromatography. Untreated cells and cells treated with 2 µM daunorubicin hydrochloride (DRB) were used as negative and positive controls, respectively. Apoptosis factors, including the level of ATP, apoptotic‑bodies by terminal deoxynucleotidyl transferase‑mediated dUTP nick end labeling (TUNEL) assay, DNA damage and the level of caspase 3/7 were analyzed. Cells treated with sevoflurane showed a significant reduction in ATP compared with untreated cells. Effects in the DRB group were greater than in the sevoflurane group. The difference of TUNEL staining between the sevoflurane and untreated groups was statistically significant. DNA degradation was observed in the sevoflurane and DRB groups, however this was not observed in the untreated group. The sevoflurane and DRB groups induced increased caspase 3/7 activation compared with untreated cells. These results suggest that sevoflurane induces apoptosis in A549 cells. In conclusion, 5% sevoflurane induced apoptosis of A549 lung alveolar epithelial cells, which resulted in decreased cell viability, increased apoptotic bodies, impaired DNA integrality and increased levels of caspase 3/7.

Drugs of anaesthesia and cancer

Anaesthesia represents one of the most important medical advances in history, and, nowadays, can widely be considered safe, thanks to the discovery of new drugs and the adoption of modern technologies. Nevertheless, anaesthetic practices still represent cause for concern regarding the consequences they produce. Various anaesthetics are frequently used without knowing their effects on specific diseases: despite having been reported that invasion or metastasis of cancer cells easily occurs during surgical procedures, numerous anaesthetics are used for cancer resection even if their effect on the behaviour of cancer cells is unclear. Guidelines for a proper use of anaesthetics in cancer surgery are not available, therefore, the aim of the present review is to survey available up-to-date information on the effects of the most used drugs in anaesthesia (volatile and intravenous anaesthetics, nitrous oxide, opioids, local anaesthetics and neuromuscular blocking drugs) in correlation to cancer. This kind of knowledge could be a basic valuable support to improve anaesthesia performance and patient safety.

Mitochondria are involved in stress response of A549 alveolar cells to halothane toxicity

During inhalation anaesthesia lung epithelial cells are directly exposed to halogenated hydrocarbons such as halothane. Information about the effects of volatile anaesthetics on lung cells is rather limited although their noxious effect on the A549 alveolar cells has been shown recently. The present study indicated that halothane decreases cell viability, impairs DNA integrity and provokes stress-induced apoptosis in A549 cells when applied at clinically relevant concentrations. Data obtained clearly demonstrated intensive expression of anti-apoptotic Bcl-2 protein during treatment with all tested concentrations. In post-treatment periods the increased DNA injury was accompanied by reduction of Bcl-2 expression. We concluded that the in vitro effect of halothane on lung cells involved alteration in the expression of proteins of the mitochondrial apoptotic pathway.

Halothane affects focal adhesion proteins in the A 549 cells

Halothane is a volatile anaesthetic, which is known to induce alterations in cellular plasma membranes, modulating the physical state of the membrane lipids and/or interacting directly with membrane-bound proteins, such as integrin receptors. Integrin-mediated cell adhesion is a general property of eukaryotic cells, which is closely related to cell viability. Our previous investigations showed that halothane is toxic for A 549 lung carcinoma cells when applied at physiologically relevant concentrations and causes inhibition of adhesion to collagen IV. The present study is focused on the mechanisms underlying halothane toxicity. Our results imply that physiologically relevant concentrations of halothane disrupt focal adhesion contacts in A 549 cells, which is accompanied with suppression of focal adhesion kinase activity and paxillin phosphorylation, and not with proteolytic changes or inhibition of vinculin and paxillin expression.We suggest that at least one of the toxic effects of halothane is due to a decreased phosphorylation of the focal contact proteins.

Volatile anaesthetic halothane causes DNA damage in A549 lung cells

The present study was performed to elucidate the extent of damage and the ability of lung epithelial cells to recover or to undergo apoptosis after in vitro treatment with the volatile anaesthetic halothane. The results obtained from the comet assay clearly show that halothane, applied at 3.0mM concentration, causes DNA and cell damage. Cells exhibited nuclear fragmentation and budding early after treatment and these events gradually increased during the next few days. The presence of a large number of mini-comets after single cell gel electrophoresis was found to represent apoptotic bodies with fragmented DNA. Our results demonstrate apoptosis-like changes after in vitro exposure of A549 cells to the volatile anaesthetic halothane. The majority of the affected cells did not recover and were directed to cell death.

Effect of isoflurane on proliferation and Na+,K+-ATPase activity of alveolar type II cells injured by hydrogen peroxide

The influence of isoflurane (Iso) on proliferation and Na+,K+-ATPase activity of alveolar type II cells (ATII cells) injured by hydrogen peroxide (H2O2) was investigated. ATII cells isolated and purified from adult Sprague-Dawley rats were randomly divided into six groups: control group, 0.28 mM Iso group, 2.8 mM Iso group, 75 microM H2O2 group, 75 microM H2O2 + 0.28 mM Iso group, and 75 microM H2O2 + 2.8 mM Iso group. After primary culture for 32 hours, the proliferation of ATII cells was detected by MTT assay, and after culture for 24 hours the activity of Na+,K+-ATPase and lactate dehydrogenase (LDH) in the cells, and malonaldehyde (MDA) content of the culture medium, were measured by colorimetry. It was found that 0.28 mM and 2.8 mM Iso had no effect on the proliferation of ATII cells (p > 0.05), but 75 microM H2O2 inhibited their proliferation (p < 0.05) compared with untreated controls; 0.28 mM and 2.8 mM Iso significantly decreased Na+,K+-ATPase activity of ATII cells compared with untreated control cells (p < 0.05), and 75 microM H2O2 markedly decreased Na+,K+-ATPase activity of ATII cells (p < 0.01) with untreated control cells. 0.28 mM and 2.8 mM Iso aggravated the decrease of Na+,K+-ATPase activity induced by H2O2. Iso had no effect on LDH activity and MDA content of the culture medium of normal ATII cells, but significantly increased LDH activity and MDA content of the culture medium of ATII cells injured by H2O2. These findings suggest that Iso itself may decrease the activity of Na+,K+-ATPase of ATII cells in vitro and further damage the cells' function under peroxidation conditions, but has no effect on the proliferation of ATII cells.