You have accessJournal of UrologyPediatrics: Basic Research1 Apr 2010281 PRIMARY MEGAURETER CONTRACTILE FUNCTION IN SITU AND IN VITRO Irina Mudraya, Zuchra Sabirzyanova, and Irina Kazanskaya Irina MudrayaIrina Mudraya More articles by this author , Zuchra SabirzyanovaZuchra Sabirzyanova More articles by this author , and Irina KazanskayaIrina Kazanskaya More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.342AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The exact role of megaureter contractility in urodynamics of megaureter (MU) in the early childhood is far from being understood. We investigated MU contractions in situ and in vitro in the infants with refluxing (RMU), obstructed (OMU), and non-obstructed (NMU) megaureters. METHODS Pyeloureterosonography with diuretic load was performed in 150 infants aged from 1 month to 3 years. Evaluation of distal ureter contractile activity (CA) was based on the changes of its cross-section area (cm2) at fixed time periods (15, 30 and 45 min) after furosemid injection (0.5ml/kg) according to the formula: CA (cm2/min) = (Srelax - Scontr)* contractile rate, where Srelax and Scontr – are the values of cross-section area of the distal ureter during its relaxation and contraction, respectively. The contractile function of MU ring fragments (n=28) isolated from child during reconstructive surgery was evaluated by in vitro bath technique and isometric tension measurements (mg/mm2) during rhythmic electric field (EFS) and tonic KCl stimulation. RESULTS In situ, 75% RMU and 10% OMU, demonstrated high CA at baseline (6.8) which attained the maximal value (12.1) during the first 15 min after administration of furosemid and remained elevated (7.3) during the following 30 min. In vitro, the contractile function of these MUs was characterized by the values of 15.5+6.1 and 21.7±5.6 for the contractions induced, respectively, by EFS and KCl. In 70% OMU and 25% RMU CA was initially moderate (0.4) and it increased to a lesser degree and developed slowly than in the previous group (1.8) at 45 min. The in situ data closely correlated with in vitro contractile function of these moderately depressed MUs. They had smaller parameters of EFS and KCl contractions, respectively: 5.8±1.0, and 10.6±1.7. All NMU (100%) and 20% OMU demonstrated extremely weak (0.2) initial CA which nevertheless accelerated maximally by 5.9 at 30 min, and remained elevated during the whole examination period showing that NMU can actively enhance their activity in response to furosemid. In vitro, EFS-induced rhythmic contractions were similarly very small (2.5±0.3) while the tonic contractions induced by KCl (23.1±1.4) were preserved. CONCLUSIONS The contractile function of megaureter depends on urodynamic type of disorder and on intrinsic contractile mechanism in the smooth muscle. Activity of the wide ureter may be maintained by rhythmic phasic and slow tonic contractions. While contractile activity was strongly inhibited in the half of OMU, the most NMU demonstrated a certain tonic contractile reserve. Moscow, Russian Federation© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e111 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Irina Mudraya More articles by this author Zuchra Sabirzyanova More articles by this author Irina Kazanskaya More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...