[Calixarene C-91 stimulates Ca2+ accumulation in the myometrium mitochondria]. 
Calixarenes, owing to the ability to form supramolecular complexes with biologically important molecules and ions, can influence a course of biochemical processes and, accordingly, be considered as perspective molecular platforms for creation of physiologically active compounds.  The work purpose is to study calixarene C-91 influence on systems of active Ca ions transport which are localized in subcellular membrane structures (mitochondria, sarcoplasmic reticulum, plasma membrane) of myometrial cells.  It has been shown, that calixarene C-91 addition to incubation medium led to an increase in Ca2+ accumulation level in mitochondria.  The maximal stimulating effect was 173% and it was observed at 100 microM concentration.  It is suggested, that calixarene C-91 can enter mitochondria with the subsequent precipitation of Ca ions in a matrix therefore calcium capacity increases, and as a consequence, higher Ca2+ accumulation in these structures is observed.  In a wide range of concentration (1-100 microM) calixarene C-91 did not influence a level of Ca2+ accumulation in sarcoplasmic reticulum of myometrial cells.  Titration of solubilized Ca2+, Mg2+-ATPase by calixarene C-91 (0,1-100 microM) did not cause changes in its activity.  Thus, calixarene C-91 increases Ca2+ accumulation level in mitochondria, but practically does not influence calcium pumps activity of a plasma membrane and sarcoplasmic reticulum of myometrial cells.