Calix[4]arene C-90 selectively inhibits Ca2+,Mg2+-ATPase of myometrium cell plasma membrane.

The supramolecular compound calix[4]arene C-90 (5,11,17,23-tetra(trifluoro)methyl(phenylsulfonylimino)-methylamino-25,26,27,28-tetrapropoxycalix[4]arene) is shown to efficiently inhibit the ATP hydrolase activity of Ca2+,Mg2+-ATPase in the myometrium cell plasma membrane fraction and also in a preparation of the purified enzyme solubilized from this subcellular fraction. The inhibition coefficient I0.5 values were 20.

[Comparative study of calixarene effect on Mg2+ -dependent ATP-hydrolase enzymatic systems from smooth muscle cells of the uterus].

Investigation the influence of calyx[4]arenes C-90, C-91, C-97 and C-99 (codes are indicated) on the enzymatic activity of four functionally different Mg2+ -dependent ATPases from smooth muscle of the uterus: actomyosin ATPase, transporting Ca2+, Mg2+ -ATPase, ouabain-sensible Na+, K+ -ATPase and basal Mg2+ -ATPase. It was shown that calixarenes C-90 and C-91 in concentration 100 microM act multidirectionally on the functionally different Mg2+ -dependent ATP-hydrolase enzymatic systems. These compounds activate effectively the actomyosin ATPase (Ka = 52 +/- 11 microM [Ukrainian character: see text] 8 +/- 2 microM, accordingly), at the same time calixarene C-90 inhibited effectively activity of transporting Ca2+, Mg2+ -ATPase of plasmatic membranes (I(0,5) = 34.

[Effect of fluoroaluminate on the ATP-hydrolysing and Ca2+-transporting activity of the purified Ca2+, Mg2+-ATPase of myometrium cell plasma membranes].

Fluoroaluminate, known modulator of G-proteins, inhibits ATP-hydrolase activity of purified solubilized Ca2+, Mg(2+)-ATPase from myometrium cell plasma membranes and Ca(2+)-transporting activity of this enzyme reconstituted into azolectin liposomes: 10 mM NaF plus 10 microM AlCl3 inhibited the primary activity by 95% and--by 81%. Inhibition of purified both solubilized and reconstituted Ca2+, Mg(2+)-ATPases by fluoroaluminate evidences for the possibility of direct interaction AlF4- with this enzyme without involvement of G-protein. The sensitivity to fluoroaluminate of sarcolemmal Ca2+, Mg(2+)-ATPase from myometrium is similar to that of Ca2+, Mg(2+)-ATPase from stomach smooth muscle.

[Effect of spermine on activity of purified Ca2+, Mg2+-ATPase from plasma membranes of myometrium cells].

Effect of endogenous polyamine spermine, a relaxant of smooth muscle, on the activity of myometrium cell plasma membrane Ca2+, Mg(2+)-ATPase was studied. It was observed a tendency to activation of enzyme at the spermine concentrations 0.1-0.