RESUMEN
Using photon correlation spectroscopy, which allows investigating changes in the hydrodynamic diameter of the particles in suspension, it was shown that ultrahigh concentrations of Ca2+ (over 10 mM) induce swelling of isolated mitochondria. An increase in hydrodynamic diameter was caused by an increase of non-specific mitochondrial membrane permeability to Ca ions, matrix Ca2+ overload, activation of ATP- and Ca2+-sensitive K+-channels, as well as activation of cyclosporin-sensitive permeability transition pore. To formalize the experimental data and to assess conformity of experimental results with theoretical predictions we developed a simulation model using the hybrid functional Petri net method.
Asunto(s)
Calcio/farmacología , Ciclosporina/farmacología , Mitocondrias/efectos de los fármacos , Dilatación Mitocondrial/efectos de los fármacos , Modelos Biológicos , Animales , Calcio/metabolismo , Cationes Bivalentes , Permeabilidad de la Membrana Celular/efectos de los fármacos , Simulación por Computador , Femenino , Transporte Iónico , Canales KATP/metabolismo , Cinética , Mitocondrias/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Miometrio/química , Miometrio/metabolismo , Canales de Potasio Calcio-Activados/metabolismo , RatasRESUMEN
The influence of supramolecular macrocyclic compounds calix[4]arenes (C-97, C-99, C-107) at a concentration of 100 nM in the process of energy-dependent Ca²âº-transport in isolated mitochondria of smooth muscle, as well as autofluorescence mitochondrial coenzyme NADH, FAD and hydrodynamic diameter of these organelles was investigated. Using Ca²âº-sensitive fluorescent dye Fluo-4 AM it was shown that the selected calix[4]arenes can suppress energy-dependent accumulation of Ca²âº by mitochondria. Accumulation of Ca²âº (80 jiM in the medium) accompanied by the growth of the fluorescent probe response from a conventional unit to a value of 1,57±0,04 (n=5). Calix[4]arenes C-97, C-99, C-107 falls fluorescent signal below the 0,88±0,08, 0,92±0,08 and 0,78±0,04 respectively. Thus, the selected calix[4]arenas lead to release of previously accumulated Ca2+ from mitochondria. Under the influence of C-97 and C-99 fluorescent signal from NADH reduced to -0,11±0,02 and -0,12±0,02, respectively, in relation to the reference value - -0,05±0,01 (n=5). Analysis of fluorescence response NADH and FAD in a suspension of isolated mitochondria suggests that the effects of test compounds on the functional activity of the electron transport chain is associated with the initial stimulation of its 1-th complex and subsequent inhibition of Ca²âº-dependent NAD- containing Krebs cycle dehydrogenases. Along with this, the use of photon correlation spectroscopy to assess changes in the volume of mitochondria (their hydrodynamic diameter) under the action of selected calix[4]arenes has shown that interference with the electron transport chain leads to changes in the osmotic balance between the matrix of the mitochondria and the external environment. The result is the growth of isolated organelles volume. In particular, the hydrodynamic diameter of mitochondria increased by 22±6 % and 34±8 % (n=5) in presence of C-97 or C-99. The conclusion was done about the advisability of further studies of the calyx[4]arenes effect on smooth muscle Ca²âº-homeostase and mitochondrial bioenergetics in order to find effective modifiers of their func- tional activity.
Asunto(s)
Calcio/metabolismo , Calixarenos/farmacología , Transporte de Electrón/efectos de los fármacos , Mitocondrias Musculares/metabolismo , Miometrio/efectos de los fármacos , Fenoles/farmacología , Animales , Femenino , Flavina-Adenina Dinucleótido/metabolismo , Miometrio/metabolismo , NAD/metabolismo , RatasRESUMEN
We demonstrated using Ca(2+)-sensitive fluorescent probe, mitochondria binding dyes, and confocal laser scanning microscopy, that elimination of electrochemical potential of uterus myocytes' inner mitochondrial membrane by aprotonophore carbonyl cyanide m-chlorophenyl hydrazone (10 µM), and by a respiratory chain complex IV inhibitor sodium azide (1 mM) is associated with substantial increase of Ca2+ concentration in myoplasm in the case of the protonophore effect only, but not in the case of the azide effect. In particular, with the use of nonyl acridine orange, a mitochondria-specific dye, and 9-aminoacridine, an agent that binds to membrane compartments in the presence of proton gradient, we showed that both the protonophore and the respiratory chain inhibitor cause the proton gradient on mitochondrial inner membrane to dissipate when introduced into incubation medium. We also proved with the help of 3,3'-dihexyloxacarbocyanine, a potential-sensitive carbocyanine-derived fluorescent probe, that the application of these substances results in dissipation of the membrane's electrical potential. The elimination of mitochondrial electrochemical potential by carbonyl cyanide m-chlorophenyl hydrazone causes substantial increase in fluorescence of Ca(2+)-sensitive Fluo-4 AM dye in myoplasm of smooth muscle cells. The results obtained were qualitatively confirmed with flow cytometry of mitochondria isolated through differential centrifugation and loaded with Fluo-4 AM. Particularly, Ca2+ matrix influx induced by addition of the exogenous cation is totally inhibited by carbonyl cyanide m-chlorophenyl hydrazone. Therefore, using two independent fluorometric methods, namely confocal laser scanning microscopy and flow cytometry, with Ca(2+)-sensitive Fluo-4 AM fluorescent probe, we proved on the models of freshly isolated myocytes and uterus smooth muscle mitochondria isolated by differential centrifugation sedimentation that the electrochemical gradient of inner membrane is an important component of mechanisms that regulate Ca2+ homeostasis in myometrium cells.