Impairment of the contractile function of the myometrium in the uterus of mammals during endotoxemia hampers the organism's reproductive ability. Our work aimed to investi- gate the effects of activating ATP-sensitive potassium (K ATP ) channels with flocalin on oxytocin-induced contractile activ - ity in isolated preparations of rat uterine myometrium under experimental endotoxemia. All testing of isolated longitudinal strips of the uterine horns from sexually mature female Wistar rats, perfused at 37°C with oxygenated Krebs solution, was conducted in isometric mode. Endotoxemia was replicated by intraperitoneal injection of lipopolysaccharide at a dose of 3 mg/kg the day before the experiment. The opener of K ATP channels, flocalin, was added to the perfusion solution at con- centrations of 0.1, 1, and 10 μmol/l, against the background of 0.1 μmol/l oxytocin. It was shown that in rats with lipo- polysaccharide-induced endotoxemia, oxytocin significantly increased the contractile activity of the uterine myometrium. At the same time, flocalin dose-dependently suppressed this excessive contractile response. Specifically, the increment in the amplitude of oxytocin-induced contractions with flocalin at concentrations of 0.1, 1, and 10 μmol/l decreased by 50%, 84%, and 122%, respectively, and the acceleration of contrac- tion frequency decreased by 7%, 18%, and 47%, respectively. В.Р. Струтинський, О.І. Дячук, Р.І. Янчій 36 The oxytocin-induced increase in basal tone at 10 μmol/l of flocalin was reduced by 53%. In summary, activation of K ATP channels by flocаlin dose-dependently suppressed the increase in contractile activity of the rat uterine myometrium caused by oxytocin in rats with experimental endotoxemia, which may prevent impaired reproductive function in females. Activation of K ATP channels could potentially have therapeutic value in restoring uterine contractile function during inflammatory processes.