POTASSIUM CHANNELS OPENER PINACIDIL HAVE MULTIPLE EFFECTS ON KCl-ELICITED CONTRACTIONS OF ISOLATED NON-PREGNANT RAT UTERUS
University of Belgrade - Faculty of Veterinary Medicine, Belgrade
The effects of K+ channel opener, pinacidil on contractions provoked by contraction-stimulating KCl were investigated on isolated uterus of non-pregnant rats in oestrus. Pinacidil produced a more potent inhibition of 20 mM KCl–elicited contractions (pD2 = 6.57 M) than of 40 or 80mMKCl–elicited contractions (pD2=5.11 and 5.19 M, respectively). Glibenclamide, a selective blocker of adenosine triphosphate (ATP)-sensitive K+ (KATP) channels, antagonized the pinacidil-induced inhibition of contractions elicited by 20 mM KCl in a competitive manner. However, the pinacidil-induced inhibition of contractions provoked by 40 and 80 mM KCl glibenclamide was unable to prevent them. Pinacidil ability to completely relax the non-pregnant uterus pre-contracted with K+-rich solution suggests that K+ channelindependent mechanism(s) also plays a part in its relaxant effect.
high K+ solution, KATP channels, pinacidil, rat uterus