[Effect of heavy metal ions on superprecipitation and ATPase activity of uterine smooth muscle actomyosin activity].
The inhibiting effect of Pb2+, Zn2+ and Cd2+ on Mg(2+)-dependent superprecipitation and ATPase activity of myometrium actomyosin. The inhibiting effect of heavy metals cations on the both processes satisfies the succession: Pb2+ > Zn2+ > Cd2+. Cadmium and zinc ions in concentration of 1 mM stimulate the initial velocity (v0) of Mg(2+)-dependent superprecipitation by 25% and 80%, respectively, while the lead ions under the same concentration inhibit the initial velocity by 40%. It is possible that these results evidence for the direct effect of ions of heavy metals on active-myosin interaction (tested by v0). May be that the mechanisms of Cd2+ and Zn2+ action on the one hand and Pb2+, on the other hand, on the interaction of the contractile proteins of the uterus smooth muscle are different. Cations of Pb, Cd or Zn introduced to the incubation medium instead of Mg2+ (5 mM) also stimulate both superprecipitation and ATPase activity but the level of the both processes decreases by 65%, 20% and 5%, respectively, as compared to control (i.e. in presence of Mg2+). It is probable that the cadmium, zinc and lead cations can substitute magnesium ions in the active centre of myosine as well as in the sections of significance for the process of superprecipitation of actomyosine. At the same time the substitution is less efficient for realization of the superprecipitation reaction and ATP-hydrolase process than when magnesium ions are available in the incubation medium. EDTA and EGTA do not remove the inhibiting effect of Pb2+, Cd2+ and Zn2+ on the contractile activity and ATP-hydrolase reaction of actomyosine complex of the uterus smooth muscle. The results obtained prove that the ions of heavy metals can effect the uterus smooth muscles at the stage of actin-myosine interaction.
Labyntseva
R D
RD
A.V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv.
Ul'ianenko
T V
TV
Kosterin
S A
SA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002384:Catalysis; D011232:Chemical Precipitation; D005260:Female; D007477:Ions; D019216:Metals, Heavy / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D013552:Swine; D014599:Uterus / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
D007477:Ions; D019216:Metals, Heavy; D000255:Adenosine Triphosphate; D009218:Myosins
Vliianie ionov tiazhelykh metallov na superpretsipitatsiiu i ATP-aznuiu aktivnots' aktomiozina gladkoĭ myshtsy matki.