Abstract: AIM: To investigate the effects of iptakalim hydrochloride (Ipt) on the association and dissociation kinetic processes of [³H] P1075 binding with sulfonylurea receptor (SUR) of ATP-sensitive potassium channel (KATP) in artery smooth muscles derived from Wistar rats.METHODS: The experiments of the association and dissociation kinetic processes of KATP opener [³H] P1075 binding with endothelium-denuded aorta smooth muscles were used.RESULTS: When artery smooth muscle preparations were preincubated with Ipt 100 μmol·L^-1, the association kinetic processe of [³H]P1075 binding with SUR was retarded.The apparent association rate constant (KA) of [³H] P1075 binding with SUR was 28.3 % as much as that of control group (P<0.01).The dissociation kinetic processes of bounded [³H] P1075 with SUR was accelerated.The apparent dissociation rate constant (KD) were 3.53-fold as much as that of control group (P<0.01).Under the same experimental conditions, the effects of KATP opener Pin were similar with those of Ipt.The values of KA and KD were 35 % and 2.88-fold as much as those of control group (P<0.01).CONCLUSION: The effects of Ipt are similar with those of KATP opener Pin.Both of them have allosteric modulatory effects on KATP.They can inhibit the association kinetic processes and accelerate the dissociation kinetic processes of openers binding with KATP.

Key words: iptakalim hydrochloride, pinacidil, [³H] P1075, ATP-sensitive potassium channel, sulfonylureareceptor