Objective(s): The aims of present study were to elucidate the effect of NaHS as a H2S donor on precontracted rat trachea smooth muscle, role of epithelium and nitric oxide in this action. Materials and Methods: Tracheal rings from male adult Wistar rats were isolated and mounted in an organ bath containing Krebs–Henseleit solution under 1.5 g resting tension and contractions were recorded isometrically. After equilibrium period (60 min), cumulative concentrations of NaHS (0.2-1.2 mM) were applied on the tracheal basal tone or on the plateau of contractions induced by KCl (60 mM) or carbachol (CCh, 0.55 µM) in the absence and presence of certain antagonists and inhibitors. Results: The tracheal basal tone was unaffected by NaHS but tracheal contractions induced by KCl and CCh were attenuated by NaHS in a concentration-dependent manner (P<0.001). Removing the tracheal epithelial did not attenuate the NaHS spasmolytic effect in the tissue precontracted by KCl and CCh. The bronchodilatory effect was unaffected by tissue incubation (30 min, 1 µM) with, glibenclamide, propranolol, indomethacin, methylene blue (10 µM), and L-NAME (300 µM). Conclusion: It seems that bronchodilatory effect of H2S was not mediated by KATP channels, b-adrenoceptors, epithelium and production of nitric oxide, cGMP and prostaglandins. Since CCh and KCl activate Ca2+ influx and CCh promotes Ca2+ from intracellular pool as well, therefore, we may conclude that the relaxant effect of NaHS was mediated by the Ca2+ influx blockade and cholinergic receptors inactivation. This preliminary study shows the possible therapeutical property of H2S in obstructive pulmonary diseases.

Background: Hydrogen sulfide (H2S) suicides have been frequent in Japan in recent years. This study was performed to describe the epidemiologic profile of an outbreak of H2S suicides in Japan.Methods: In September 2008, questionnaires about patients involved in H2S suicides were sent to 250 hospitals in Japan. Data collected from each patient included gender, age, clinical manifestations, date of event, location of suicide, source of H2S, treatments and neurological outcome.Results: A total of 90 subjects (60 men, 30 women) were enrolled in this study. In this outbreak, the first case was reported in September 2006 and subsequent cases reached a peak in April 2008. There were 60 cases of attempted suicide by generating H2S gas (suicide group) and 30 cases of secondary exposure (secondary exposure group). The suicide group included mostly subjects in their twenties. Cardiopulmonary arrest at the scene was reported in 39 cases (65%). Clinical features of the suicide group inpatients included coma (14 cases), convulsion (1 case), and lung edema (1 case). Patients in suicide group were significantly younger than secondary exposure group (P<0.001). The development of cardiopulmonary arrest was significantly higher in suicide group (65% vs. 10%; P<0.001). Death was more frequent in suicide group (70% vs. 10%; P<0.001) and patients with secondary exposure were discharged with better neurological outcomes (Table 1).Conclusion: Suicide with H2S poisoning has recently been a serious social problem especially in younger generation in Japan. There is extensive information on H2S suicide methods on the internet. Management of access to websites describing suicide methods is an immediate necessity together with counseling for suicide prevention.

In this research, reactive absorption of Hydrogen sulfide using diglycolamine solution in an industrial tray column was investigated. A nonequilibrium stage model has been developed based on dynamic film model for modeling of Hydrogen sulfide reactive absorption into diglycolamine solution. In the model, simultaneous heat and mass transfer and reactions rate were considered. The model equations including partial and ordinary differential equations were solved numerically using the method of lines technique. The simulation results are presented in steady and unsteady state conditions. An industrial absorption column was employed to obtain the experimental data in both low and high pressure. The model results were evaluated using the steady state experimental data. A comparison of the experimental and simulation results showed that the average of correlation coefficient error for high pressure absorption process is 8.5 percent whereas the average of correlation coefficient error for low pressure absorption process is 7 percent.