Inactivation of human alpha 1-proteinase inhibitor by cigarette smoke: effect of smoke phase and buffer

In order to resolve a discrepancy in the literature, we have examined the in vitro inactivation of human alpha 1-proteinase inhibitor by direct exposures either to whole cigarette smoke or to filtered (i.e., gas-phase) smoke. Wyss and coworkers (2) reported that whole smoke does not inactivate the protein, whereas we reported that gas-phase smoke does. We now find that direct exposure to gas-phase cigarette smoke causes a slightly greater inactivation of the protein than does direct exposure to whole cigarette smoke, confirming our earlier suggestion that whole smoke is less oxidizing than is gas-phase smoke. This difference, however, does not explain the dramatic difference between our previous findings and those of Wyss and coworkers (2). The explanation for the discrepancy lies in the nature of the buffers used. Wyss and coworkers used Tris buffer and the use of Tris quenches the inactivation process almost completely. Our experiments used phosphate buffer. We suggest that Tris is an unsuitable buffer for use in experiments that probe the effects of cigarette smoke.     

Direct effect of cigarette smoke on human pulmonary artery tension

The effect of chronic cigarette smoke on pulmonary artery (PA) tension has been studied extensively; nevertheless, the direct effect of cigarette smoke is poorly understood. We investigated the direct effect of cigarette smoke extract (CSE) on PA tension in non-smokers, smokers, and COPD patients in vitro. PA samples from 35 patients who underwent lung resection were examined by measuring isometric tension in response to increasing serotonin concentrations. CSE dose dependently inhibited the response to serotonin in smokers and COPD patients, and to a lesser extent in non-smokers. CSE-induced relaxation was similarly inhibited by the nonspecific nitric oxide synthase (NOS) inhibitor l-NOARG and the specific inducible NOS (iNOS) inhibitor l-NIL, mainly in non-smokers and smokers, and to a lesser extent in COPD patients. Immunostaining of iNOS in PA samples was greater for smokers and COPD patients compared with non-smokers, which explains the lesser effect of CSE on PA tension in non-smokers. Moreover, CSE induced the release of nitrite via iNOS in human PA smooth muscle cells. In conclusion, CSE inhibition of serotonin-induced PA contraction was mediated mainly by iNOS in non-smokers, smokers, and COPD patients, but in different ways, which may be explained by differential iNOS expression in the PA of these patients.     

The effect of cigarette smoke on bleomycin-induced pulmonary fibrosis in hamsters

To investigate the effect of cigarette smoke on the development of bleomycin (BLM)-induced pulmonary fibrosis in hamsters, four experimental groups were studied: a control group (C), a cigarette smoke-inhaled group (T), a BLM-administered group (B), and a cigarette smoke-inhaled plus BLM-administered group (TB). Groups T and TB were exposed to sidestream smoke of cigarettes for 30 min/day, 5 days/wk. Groups B and TB were administered 0.5 mg BLM hydrochloride per 100 g body weight endotracheally once on day 30 (Day 0) after housing start. Quantitative morphometry of the lungs revealed that Group TB showed less lung fibrotic change compared with Group B, but based on qualitative observation, the fibrotic lesions of Group TB were intermingled with slight emphysematous changes. Neutrophils in bronchoalveolar lavage fluid were remarkably increased in both the groups, with a peak on Day 1, but the increase in Group TB lasted longer. Alveolar macrophages were increased in both smoking groups (T and TB) compared to the non-smoking groups (C and B). These results suggest that cigarette smoke reduces BLM-induced lung fibrotic changes; however, it simultaneously causes derangement of alveolar architecture. The persistence of increased neutrophils in the early phase after BLM accompanied by exposure to cigarette smoke may play an important role in the mechanism by which smoke ameliorates the effect of BLM.     

Bronchoconstriction and delayed rapid shallow breathing induced by cigarette smoke inhalation in anesthetized rats

Bronchomotor and ventilatory responses to inhalation of cigarette smoke (50% concentration, 6 ml) were studied in anesthetized and vagotomized Sprague-Dawley rats. Low-nicotine cigarette smoke did not cause any detectable delayed response, whereas high-nicotine cigarette smoke induced rapid, shallow breathing, and a marked increase in airway resistance (RL). The increase in f reached a peak (delta f = 43 +/- 8%) at the 5th breath after the onset of smoke inhalation, preceding both the decrease in VT (delta VT = -27 +/- 4%) and the increase in RL (delta RL = 89 +/- 19%); the latter 2 reached their peaks at approximately the 10th breath, displaying a similar temporal pattern of responses between them. The bronchomotor response to high-nicotine cigarette smoke was slightly attenuated but not prevented by prior administration of isoproterenol (0.2 mg/kg, intravenously [iv]), nor was the smoke-induced rapid, shallow breathing. In contrast, prior administration of mecamylamine (0.9 mg/kg, iv) completely abolished both the bronchomotor and ventilatory responses to smoke inhalation, indicating that nicotine is the primary causative agent responsible for these changes.     

Bronchoconstriction and delayed rapid shallow breathing induced by cigarette smoke inhalation in anesthetized rats

Bronchomotor and ventilatory responses to inhalation of cigarette smoke (50% concentration, 6 ml) were studied in anesthetized and vagotomized Sprague-Dawley rats. Low-nicotine cigarette smoke did not cause any detectable delayed response, whereas high-nicotine cigarette smoke induced rapid, shallow breathing, and a marked increase in airway resistance (R_L). The increase in f reached a peak (Δf=43±8%) at the 5th breath after the onset of smoke inhalation, preceding both the decrease in V_T (ΔV_T=−27±4%) and the increase in R_L (ΔR_L=89±19%); the latter 2 reached their peaks at approximately the 10th breath, displaying a similar temporal pattern of responses between them. The bronchomotor response to high-nicotine cigarette smoke was slightly attenuated but not prevented by prior administration of isoproterenol (0.2 mg/kg, intravenously [iv]), nor was the smoke-induced rapid, shallow breathing. In contrast, prior administration of mecamylamine (0.9 mg/kg, iv) completely abolished both the bronchomotor and ventilatory responses to smoke inhalation, indicating that nicotine is the primary causative agent responsible for these changes.     

Adverse effects of cigarette smoke on NO bioavailability: role of arginine metabolism and oxidative stress

Endothelial dysfunction is a hallmark of cardiovascular disease, and the l-arginine:NO pathway plays a critical role in determining endothelial function. Recent studies suggest that smoking, a well-recognized risk factor for vascular disease, may interfere with l-arginine and NO metabolism; however, this remains poorly characterized. Accordingly, we performed a series of complementary in vivo and in vitro studies to elucidate the mechanism by which cigarette smoke adversely affects endothelial function. In current smokers, plasma levels of asymmetrical dimethyl-arginine (ADMA) were 80% higher (P = 0.01) than nonsmokers, whereas citrulline (17%; P < 0.05) and N-hydroxy-l-arginine (34%; P < 0.05) were significantly lower. Exposure to 10% cigarette smoke extract (CSE) significantly affected endothelial arginine metabolism with reductions in the intracellular content of citrulline (81%), N-hydroxy-l-arginine (57%), and arginine (23%), while increasing ADMA (129%). CSE significantly inhibited (38%) arginine uptake in conjunction with a 34% reduction in expression of the arginine transporter, CAT1. In conjunction with these studies, CSE significantly reduced the activity of eNOS and NO production by endothelial cells, while stimulating the production of reactive oxygen species. In conclusion, cigarette smoke adversely affects the endothelial l-arginine NO synthase pathway, resulting in reducing NO production and elevated oxidative stress. In conjunction, exposure to cigarette smoke increases ADMA concentration, the latter being a risk factor for cardiovascular disease.     

Involvement of hydroxyl radical in the immediate ventilatory responses to inhaled wood smoke in rats

Spontaneous inhalation of wood smoke (∼6 ml) via a tracheostomy immediately triggered either a slowing of respiration (SR, n=51) or an augmented inspiration (AI, n=32) in 83 anesthetized Sprague-Dawley rats studied. To investigate the involvement of hydroxyl radical (OH^⋅) in evoking these immediate smoke-induced ventilatory responses, smoke challenges were repeated following intravenous infusion (0.05 ml/min for 20 min) of saline vehicle, dimethylthiourea (DMTU, 500 mg/kg), deferoxamine (DEF, 20 mg/kg), or iron-saturated DEF (DEF+Fe, 20 mg/kg). DMTU is a scavenger for OH^⋅. DEF is an iron-chelator which prevents the formation of OH^⋅, whereas DEF saturated with iron results in the loss of its iron-chelating properties. In the vehicle group, both the SR (n=8) and the AI (n=7) were unaffected by the pretreatment. However, in the DMTU group, the SR (n=23) was abolished in seven and attenuated in 16 rats, while the AI (n=10) was eliminated in eight and unaffected in two rats. In the DEF group, the SR (n=12) was abolished in three and attenuated in nine rats, while the AI (n=8) was eliminated in six and unaffected in two rats. In contrast, in the DEF+Fe group, both the SR (n=8) and the AI (n=7) were not attenuated by the pretreatment. These results suggest that an increase in OH^⋅ burden following smoke inhalation is actively involved in evoking the acute irritant effects of wood smoke on breathing in rats.     

The differential effect of cigarette smoke on the growth of bacteria found in humans

The effect of cigarette smoke on growth of those species of bacteria that are considered common potential human pathogens was examined in vitro. Smoke from both mentholated and nonmentholated cigarettes inhibited the growth of Gram-positive cocci to a greater degree than that of Gram-negative rods. Staphylococcus aureus, Streptococcus pneumoniae, and a variety of other streptococci were inhibited at a smoke solution dilution of 1:8. Enteric bacteria such as Klebsiella, Enterobacter, and Pseudomonas were not affected by a 1:1 dilution of the solution. As with the Gram-positive cocci, the Neisseria species and Branhamella were also inhibited at a dilution of 1:8. Culture results of the mouth of 15 smokers and 15 nonsmokers showed that the smokers have a propensity to develop heavy Gram-negative bacterial colonization.     

The additive effect of ethanol and extract of cigarette smoke on rabbit esophagus epithelium

Aim:  The combination of alcohol and smoking takes a place in the epidemiology and pathogenesis of gastroesophageal reflux disease and squamous cancers of the esophagus. Therefore, a study was designed to assess the impact of these agents alone or in combination on the structure and function of squamous epithelium of rabbit esophagus.
Methods:  Rabbit esophageal epithelium was mounted in Ussing Chambers, exposed luminally for ethanol (1–10%), extract of cigarette smoke (EOCS) and combinations or sequential application of these agents. An in-vivo model was also used to mimic conditions more representative of human alcohol consumption.
Results:  Ethanol (1–10%) dose dependently decreased tissue resistance. Extract of cigarette smoke caused a reduction on transepithelial potential difference (PD), short circuit current. Combinations of EOCS, ethanol (5–10% EtOH and EOCS 1–2) showed a more pronounced decrease than agents alone, mainly the result of EOCS. In vivo studies showed that EOCS administration dropped PD dose dependently. In-vivo 10% EtOH, EOCS-2 dropped PD (55%) similar to in-vitro 5% EtOH, EOCS-1. The effect was clearly additive; boluses of 10% ethanol (36%) and EOCS-2 (17%) decreased PD and combination of agents resulted in a 55% drop on PD which is a very similar decrease compared to the sum of the separate effects of agents (53%).
Conclusion:  Ethanol affected the barrier and cigarette smoke altered ion transport on rabbit esophageal epithelium under conditions reflecting human consumption. Results were consistent with in vivo and in vitro conditions except higher concentrations were needed in vivo . When applied, these agents showed an additive effect. Ethanol predisposed the tissue to the effect of EOCS.     

Differential in vivo effects of whole cigarette smoke exposure versus cigarette smoke extract on mouse ciliated tracheal epithelium

In this study the authors compared the affect of vapor phase cigarette smoke (CS) versus cigarette smoke extract (CSE) on the lungs and upper airway of C57BL/6 mice. The authors found that CSE treatment significantly increased neutrophil influx (P < .001), baseline ciliary beat frequency (CBF) (P < .05), and protein kinase C activity compared to CS and controls. Isoproterenol increased CBF with CS exposure, but decreased CBF with CSE (P < .01). Isoproterenol increased protein kinase A (PKA) activity in all groups except CSE. CSE exposure induced inflammatory cell bronchiolitis. These data indicate that CSE exposure has differential effects on the lungs and tracheal epithelium compared to CS exposure.     

吸烟对大鼠肺动脉压和一氧化氮合酶的影响

目的 :探讨长期吸烟对大鼠肺动脉压及一氧化氮合酶的影响。方法 :SD雄性大鼠 40只 ,随机分为吸烟组和对照组 ,吸烟组暴露于点燃之烟卷 ,每日 6 h,于 9个月时检测吸烟组及对照组大鼠的肺动脉平均压 （m PAP）、血清一氧化氮 （NO）、肺动脉结构型一氧化氮合酶 （c NOS）和诱导型一氧化氮合酶 （i NOS）。结果 :吸烟组大鼠 m PAP明显高于对照组 ,血清 NO浓度与对照组相比明显减低 ,吸烟组肺细小动脉 c NOS平均吸光度值较对照组明显降低 ,吸烟组大鼠肺细小动脉 i NOS的平均吸光度值较对照组明显增高。结论 :烟雾可致肺动脉高压的形成 ,抑制肺细小动脉 c NOS表达、促进肺细小动脉 i NOS表达可能为其重要作用机制之一。     

Particulate and vapor phase constituents of cigarette mainstream smoke and risk of myocardial infarction

On pharmacological and compositional grounds, cigarette mainstream smoke (MS) aerosol can be broadly categorized as consisting of the following constituents: carbon monoxide, other vapor phase components, particulate matter ('tar') and nicotine. The relative risk of coronary artery disease for smoking 20 cigarettes per day has been estimated by meta-analysis of five large prospective epidemiology studies to be 1.78. These four major smoke components are simultaneously delivered to the active smoker as a complex aerosol composed of several billion semi-liquid particles per cm(3) within the mixture of combustion gases. Fractional attribution of the 78% increase in reported risk to a given constituent is problematic because of the complex mixture. However, a significant literature exists which suggests that some general statements regarding smoke constituent-associated risks for development or exacerbation of myocardial infarction are supportable. First, the atherogenic potential of MS is associated with the particulate and vapor phases and not with CO. Nicotine might exert an indirect effect on atherosclerotic plaque development by increasing shear forces in main conduction arteries. Similarly, the thrombogenic potential is associated primarily with the particulate and vapor phases and also possibly with nicotine via platelet aggregation. Vasoconstriction probably results from the actions of nicotine and hypoxia from carbon monoxide. Finally, the arrhythmia-inducing potential may result from catecholamine release following nicotine exposure, with a questionable contribution from carbon monoxide.