Effect Of Kaempferol On The Contraction Of Isolated Longitudinal Muscle Strips Of Uterus In Rabbits

BackgroundPregnancy is a complicated physiological processes.The change of hormone concentration and jointly maintain the interaction between the contraction and relaxation of myometrium of the dynamic balance until the initiation of parturition.Premature birth is that the myometrium is so excited to lead to delivery in advance.How to effectively control the excitability of uterine smooth muscle is the key to treatment of premature birth.Kaempferol,also known as Galangal,belongs to flavonoids.It has cancer prevention,anti-cancer,antioxidant,antibacterial,antiviral and other functions.Recent material shows that kaempferol has strong role of relaxation of uterine smooth muscle for the adult rats.But how the role of relaxation of uterine smooth muscle of the rabbit has not been reported yet.ObjectivesTo investigate the effects of kaempferol on the isolated uterus smooth muscle from rabbits and its possible mechanism.Methods To make the isolated uterus smooth muscle strip, put the samples into the smooth muscle bath and incubate with the mixed gas including95%O2and5%CO2. According to the study protocol, we add the kaempferol of different concentration in advance and observe its effection on the uterine smooth muscle of the rabbits in the state of pregnancy; Add the concentration of2×10-3mol/L of kaempferol, then we put the adrenergic receptor blockers-SR59230A, cGMP channel blocker-Methylene blue,cAMP-dependent protein kinase inhibitors-Rp-cAMP, and observe the effects of kaempferol on the spontaneous contraction and analyse its possible mechanism; We put oxytocin, PGF2a and KCl into the smooth muscle bath to induce gravid uterus smooth muscle producing the strong contraction, then add the concentration of2×10-3mol/L of kaempferol, observe the effects of kaempferol on the strong contraction and analyse its possible mechanism.ResultsKaempferol (fine concentration:1×10-5mol/L,2×10-5mol/L and1×10-4mol/L) has no effect on the amplitude, tension and frequency of spontaneous contraction, but the concentration of2×10-4mol/L,1×10-3mol/L and2×10-3mol/L of kaempferol can inhibit the tension and amplitude of spontaneous contraction with dose-dependent and has no effect on frequency; Kaempferol can antagonize contraction induced by oxytocin, PGF2a and KC1in the isolated uterus smooth muscle, and the more the kaempferol concntration is, the stonger the inhibiting effect is; The relaxant effects of kaempferol on the gravid uterus smooth muscle has a tight relationship with the mediated relaxation of adrenergic β3receptor, related relaxation of cAMP and cGMP, L-type voltage compliance Ca2+channel opening and intracellular calcium release quantity.Conclusion1.Kaempferol can inhibit the tension and amplitude of spontaneous contraction with dose-dependent, which has a tight relationship with the mediated relaxation of adrenergic β3receptor, related relaxation of cAMP and cGMP. 2. Kaempferol can antagonize contraction induced by oxytocin, PGF2a and KCl in the isolated uterus smooth muscle, which is related with L-type voltage compliance Ca2+channel opening and intracellular calcium release quantity.