In children and adolescents (250 healthy subjects) serum dopamine-beta-hydroxylase (DBH) activity (23.95.2 to 57.117.5 μmol/min/ml) increases with the age between 3-10 years, later it decreases approximately by the age of 10-14 years. At the age of 21 to 60 years DBH level is stable. Our study described decreasing DBH activity in adolescents at the age of 10-14 years in the studied sample of healthy persons. Experimental animals (200 Wistar rats, 5-120 days old) show the same trend of enzymatic activity, similarly as in humans. DBH activity in rats is between 0.850.1 to 2.80.05 μmol/min/ml. This activity is highest in 5-day-old rats; it decreases till the age of 14 days and increases mainly in 14- to 35-day-old animals. Decrease of DBH activity in rats between 35 to 40 days is significant and corresponds to the reduction of DBH activity in adolescent humans (10-14 years). Adult rats (aged 90-120 days) show a stable DBH activity. DBH activity intermediately decreases in 10- to 14-year-old children. This decrease corresponds to the intermediate developmental changes of electrophysiological parameters (decreasing EEG activity in healthy adolescents occurs in 10-14 years old children). Puberty is coupled with intermediate decreasing of DBH activity in man and also in experimental animals in the period of prominent psychological and physiological changes.
Erythromycin has a well-known dual effect on the contractility of the gastrointestinal system and recently has also been shown to inhibit contractions of the rat myometrium. The aim of the present study was to investigate the effects of clarithromycin on oxytocin, prostaglandin F2a (PGF2a) and KCl-induced contractions of human myometrium in vitro. Myometrial strips were obtained from pregnant women undergoing elective Cesarean section and the strips were suspended in a jacketed organ bath filled with Krebs solution at 37 oC (pH 7.4) and continuously aired with 95 % oxygen and 5 % carbon dioxide. Isometric contractions were measured using a force displacement transducer. Oxytocin, PGF2a, KCl and clarithromycin were applied to the tissue bath and the amplitude and frequency of contractions were evaluated at 20-min intervals. Freidmann analysis of variance, Kruskal Wallis and Wilcoxon Rank tests were used for statistical analysis of the data. Clarithromycin dose dependently inhibited the amplitude of contractions independent of the stimulus. Pre-treatment with apamin prevented clarithromycin-induced effects on amplitude and frequency of contractions. We conclude that the macrolide antibiotic clarithromycin may have a direct inhibitory effect on contractions of human myometrium., H. Celik, A. Ayar., and Obsahuje bibliografii