Functional changes in isolated guinea-pig papillary muscle induced by monensin and digoxin

Analysis of the Relationship Between Hemorheologic Parameters, Aluminum, Manganese, and Selenium in Smokers

Smoking is a significant risk factor in fatal pathologies including cardio-cerebrovascular and respiratory diseases. Aluminum (Al) is a toxic element without known biological function, but with recognized toxic effects. Manganese (Mn) and selenium (Se) are essential trace elements involved in cellular antioxidant defense mechanisms. Al, Mn, and Se carry out their metabolic activities via blood flow and tissue oxygenation. The structure and number of red blood cells (RBC) play important role in tissue oxygenation throughout blood flow. Increased hematocrit (Hct) as a result of probable hypoxia induces disturbed blood flow, RBC aggregation (RBC Agg), RBC deformability index (Tk), and oxygen delivery index (ODI). Therefore, we aimed to investigate the effects of altered Al, Mn, and Se levels on number, structure, and function of RBCs (Hct, blood and plasma viscosity (BV and PV, respectively), RBC Agg, Tk, ODI) in smokers without diagnosis of chronic obstructive pulmonary disease (COPD) in a study group (n = 128) categorized as ex-smokers (ES), smokers (S), and healthy controls (HC). Elements were analyzed in serum using ICP-OES. BV and PV were measured via Brookfield and Harkness viscometers at 37 °C, respectively. Smokers had statistically higher serum Al and Mn levels, BV, RBC, Hgb, Hct, PV, fibrinogen, RBC Agg, Tk₄₅, and pulmonary blood flow rate, but lower serum Se levels and ODI₄₅ values versus HC. In conclusion, increased Al, Mn, and hemorheological parameters and decreased Se and ODI₄₅ might result from inflammatory response in defense mechanism in smokers without diagnosis of COPD. Our results point out that serum Al, Mn, and Se with hemorheological parameters may be beneficial markers of tissue oxygenation and defense mechanism before the clinic onset of COPD in smokers.

Serum mineral status of long-term cigarette smokers

This study was carried out to investigate comparatively some serum mineral levels of cigarette smokers. A total of 25 nonsmokers (control group) and 50 long-term cigarette smokers (smoking for at least 15 years; smoker group) were participated in the study. Subjects were between 25 and 40 years old. Control and smoker groups were matched for age, sex and body mass index status. The blood samples were taken from smokers and nonsmokers after 12 h of fasting period. The levels of zinc (Zn), copper (Cu), iron (Fe), magnesium (Mg), calcium (Ca), potassium (K), chlorine (Cl), sodium (Na) and phosphorus (P) were measured by autoanalyzer using commercial kits. Student’s t test was used to compare the control and smoker groups, and p < 0.05 indicated a significant difference. Pearson’s correlation coefficient was used to demonstrate the relationship among parameters in smoker and control groups. Although there was no statistical difference ( p > 0.05) between the groups regarding the levels of K, P, Mg, Na, Cl, Zn, Fe, Ca and Cu, some positive correlations were observed in controls but not in smokers. Therefore, it was concluded that smoking does not affect the serum mineral levels. However, it may negatively affect some important positive correlations among minerals observed in healthy individuals.

Digoxin- and monensin-induced changes of intracellular Ca2+ concentration in isolated guinea-pig ventricular myocyte

This study was undertaken to determine the possible mechanisms of actions of monensin and digoxin by using isolated guinea-pig ventricular myocytes. Since Ca2+ is the major signal for triggering contraction of cardiac muscle, the objective of this study was to determine whether monensin and digoxin affect the [Ca2+]i of cardiac myocytes and if so is this effect due to an increase in [Na+]i. Three different concentrations of digoxin (0.3, 1 and 3 micromol/l) and three different concentrations of monensin (0.3, 1 and 3 micromol/l) were used. Each treatment was monitored for two hours by using computerized fluoroscopy. Both digoxin and monensin increased the [Ca2+]i and accelerated the onset time of [Ca2+]i increase in a dose-dependent manner. Normal myocytes (loaded with fura-2 for 30 min before the treatment) were also compared with 'weakened' myocytes (loaded with fura-2 for 3 h before the treatment to create a 'weakened' condition). It was found that although 0.3 micromol/l monensin and digoxin did not change the [Ca2+]i in normal myocytes, they increased the [Ca2 +]i in 'weakened' myocytes. Finally, a Na+-free medium was used to demonstrate the effect of [Na+]o on both monensin- and digoxin-induced increases in [Ca2+]i. It was found that digoxin did not increase the [Ca2+]i in the Na+-free medium. Although monensin increased the [Ca2+]i in the Na+-free solution, this increase was not as large as in the Na+-containing medium. The results of the study led to the conclusion that the positive inotropic effect of digoxin depends on [Na+]o. However, monensin increases [Ca2+]i in Na+-dependent and -independent ways. An addition conclusion was that 'weakened' myocytes are more sensitive to the monensin and digoxin treatment than normal myocytes.