Ca(2+)-dependent regulation of the Ca(2+) concentration in the myometrium mitochondria. I. Trifluoperazine effects on mitochondria membranes polarization and [Ca(2+)](m)

Abstract

Са2+-dependent regulation of Ca2+ exchange in mitochondria is carried out with participation of calmodulin. We have shown previously that calmodulin antagonists reduced the level of mitochondrial membrane polarization and induced increase of the ionized Са concentration in both the mitochondrial matrix and cell cytoplasm. The concentration-dependent influence of trifluoperazine on the level of polarization of mitochondrial membranes has been shown in this work. The coordinates of the Hill graphs were used to calculate the constant K0.5 and the Hill coefficient. K0.5 was 24.4 ± 5 μM (n = 10). The Hill coefficient was 2.0 ± 0.2, indicating the presence of two centers of the trifluoperazine binding. We have also studied [Ca2+]m changes, when incubating mitochondria in mediums of different composition: without ATP and ions of Mg (0-medium), in the presence of 3 mM Mg (Mg-medium) and 3 mM Mg + 3 mM ATP (Mg,ATP-medium). It was shown that the composition of the incubation medium affected the [Ca2+]m values in the absence of exogenous Ca2+ and did not affect them in the presence of the latter. Preincubation of mitochondria in mediums of different composition with 25 μM trifluoperazine did not affect the [Ca2+]m values both before and after the addition of 100 µМ Са2+ to the incubation medium. It was concluded, that trifluoperazine depolarized myometrial mitochondria membranes in concentration-dependent manner. However, mitochondria preincubation with 25 μM trifluope­razine accompanied by 50% decrease in membrane polarization did not affect the [Ca2+]m values.

Ca(2+)-dependent regulation of the Ca(2+) concentration in the myometrium mitochondria. II. Ca(2+) effects on mitochondria membranes polarization and [Ca(2+)](m)

“…We have shown previously that calmodulin antagonists caused depolarization of mitochondrial membranes and an increase of the ionized Са concentration in both the mitochondrial matrix and the cell cytoplasm [9]. At the first part of this paper we have shown the concentration-dependent influence of calmodulin antagonist trifluoperazine on the level of mitochondrial membranes polarization with k 0.5 24.4 ± 5.0 μM and the Hill coefficient 2.0 ± 0.2 [10]. But it was also shown that preincubation of isolated mitochondria in mediums of different composition with 25 μM trifluoperazine did not affect the [Ca 2+ ] m values both before and after the addition of 100 μМ Са 2+ .…”

Сalix[4]arene chalcone amides effects on myometrium mitochondria

“…Mitochondria, loaded with a fluorescent probe, were incubated without (control) or with 10 µM calix [4]arenes during 5 min in Mg 2+ -or Mg 2+ ,ATP-containing medium in the absence of exogenous Ca 2+ . As we have shown previously , ATP addition to the Mg 2+ -containing medium resulted in [Ca 2+ ] m (in the absence of exo genous Ca 2+ ) [28] and total Са 2+ accumulation increase [27]. The results of each experiment were normalized to 100% of the control sample.…”

Сalix[4]arene Chalcone Amides—The Nanosize Modulators of Polarization of Mitochondrial Membranes and Content of the Ionized Ca in Them

“…Ó попередніх роботах ми показали, що введення АТР до середовища інкубації, що містить Mg 2 , супроводжується зростанням рівня ендогенного Са у матриксі мітохондрій [17] та істотно збільшує загальний рівень акумуляції Са 2 у цих структурах [16]. Отже наступну серію експериментів ми провели у середовищі, що містить Mg 2+ ,АТР.…”

“…Цікавим є той факт, що калікс [4]арени з більшою ефективністю проявили себе у середовищі, що містить Mg 2+ , АТР. Íаші попередні результати показали, що за таких умов мітохондрії мають найбільшу Са 2 -акумулюючу активність, що супроводжується як зростанням загального рівня накопичення Са 2+ [16], так і його йонізованої форми [17].…”