The metabolic inhibition and contractily in rat myometrium: role of energy sources and cellular buffers

2. ABSTRACT The aim of this study was to investigate the role of different pH buffers, different energy sources and role of ion channels in metabolic stress induced by KCN on contractility of myometrium. Myometrial strips were isolated from virgin adult Wistar rats after cervical dislocation and suspended in an isolated tissue bath containing Krebs solution continuously bubbled with 95%02 and 5%C02 maintained at 37°C'de (pH 7.4). After manifestation of spontaneous contractions following equilibrium under resting tension potassium cyanide (KCN), pyruvate, glybenclamide or tetra ethyl ammonium (TEA) was applied to the tissue bath. The amplitüte and frequency of contractions were evaluated by 10-min intervals. Wilcoxon rank test was used for statistical analysis of data. KCN (0.5 or 1 mM) gradually inhibited the spontaneous contractions, being more effective in experiments where NaHC03 was used in Krebs solution instead of HEPES. This inhibition was reversed by pyruvate (10 mM) and K+ channel blocker TEA. Application of ATP- sensitive K+ channel blocker glybenclamide did not reverse KCN-induced inhibition of myometrial contractions. In conclusion, results from this study indicates that K+ channels plays a role, at least partially, in KCN-induced inhibition of myometrial contractions of rat and this inhibition can be reversed by pyruvate. Key Words: Myometrium, contraction, pyruvate, pH, TEA, KCN, glybenclamide.