The calixarene C-107 increases the affinity of the Na+,K(+)-ATPase in plasmatic membrane of smooth muscle cells to the ouabain

In the experiments carried out with the suspension of the myometrium cell plasmatic membranes treated with 0.1% digitonin solution we investigated the influence of calixarene C-107 (5,17-diamino(2-pyridyl)methylphosphono-11,23-di-tret-butyl-26,28-dihydroxy-25,27-dipropoxyca-lix4]arene) on the Na+,K(+)-ATPase activity. It was shown that this calixarene increased the affinity of the enzyme for the sodium pump conventional inhibitor - ouabain: the magnitudes of the seeming constant of inhibition I0.5 changed from 26.9 +/- 1.3 mM to 10.9 +/- 0.6 mM. However the ouabain itself did not influence on the affinity of the Na+,K(+)-ATPase for calixarene C-107.