The Identification of Prohibitin in the Rat Heart Mitochondria in Heart Failure

Mitochondria are considered the main organelles in the cell. They play an important role in both normal and abnormal heart function. There is a supramolecular organization between the complexes of the respiratory chain (supercomplexes (SCs)), which are involved in mitochondrial respiration. Prohibitins (PHBs) participate in the regulation of oxidative phosphorylation (OXPHOS) activity and interact with some subunits of the OXPHOS complexes. In this study, we identified a protein whose level was decreased in the mitochondria of the heart in rats with heart failure. This protein was PHB. Isoproterenol (ISO) has been used as a compound to induce heart failure in rats. We observed that astaxanthin (AX) increased the content of PHB in rat heart mitochondria isolated from ISO-injected rats. Since it is known that PHB forms complexes with some mitochondrial proteins and proteins that are part of the complexes of the respiratory chain, the change in the levels of these proteins was investigated under our experimental conditions. We hypothesized that PHB may be a target for the protective action of AX.

Functional State of Rat Heart Mitochondria in Experimental Hyperthyroidism

In this work, the effect of thyroxine on energy and oxidative metabolism in the mitochondria of the rat heart was studied. Hyperthyroidism was observed in experimental animals after chronic administration of T4, which was accompanied by an increase in serum concentrations of free triiodothyronine (T3) and thyroxine (T4) by 1.8 and 3.4 times, respectively. The hyperthyroid rats (HR) had hypertrophy of the heart. In HR, there was a change in the oxygen consumption in the mitochondria of the heart, especially when using palmitoylcarnitine. The assay of respiratory chain enzymes revealed that the activities of complexes I, I + III, III, IV increased, whereas the activities of complexes II, II + III decreased in heart mitochondria of the experimental animals. It was shown that the level of respiratory complexes of the electron transport chain in hyperthyroid rats increased, except for complex V, the quantity of which was reduced. The development of oxidative stress in HR was observed: an increase in the hydrogen peroxide production rate, increase in lipid peroxidation and reduced glutathione. The activity of superoxide dismutase in the heart of HR was higher than in the control. At the same time, the activity of glutathione peroxidase decreased. The obtained data indicate that increased concentrations of thyroid hormones lead to changes in energy metabolism and the development of oxidative stress in the heart of rats, which in turn contributes to heart dysfunction.

Mitochondrion as a Target of Astaxanthin Therapy in Heart Failure

Mitochondria are considered to be important organelles in the cell and play a key role in the physiological function of the heart, as well as in the pathogenesis and development of various heart diseases. Under certain pathological conditions, such as cardiovascular diseases, stroke, traumatic brain injury, neurodegenerative diseases, muscular dystrophy, etc., mitochondrial permeability transition pore (mPTP) is formed and opened, which can lead to dysfunction of mitochondria and subsequently to cell death. This review summarizes the results of studies carried out by our group of the effect of astaxanthin (AST) on the functional state of rat heart mitochondria upon direct addition of AST to isolated mitochondria and upon chronic administration of AST under conditions of mPTP opening. It was shown that AST exerted a protective effect under all conditions. In addition, AST treatment was found to prevent isoproterenol-induced oxidative damage to mitochondria and increase mitochondrial efficiency. AST, a ketocarotenoid, may be a potential mitochondrial target in therapy for pathological conditions associated with oxidative damage and mitochondrial dysfunction, and may be a potential mitochondrial target in therapy for pathological conditions.

N-Alkylation of Anthracycline Antibiotics by Natural Sesquiterpene Lactones as a Way to Obtain Antitumor Agents with Reduced Side Effects

Anthracycline antitumor antibiotics are one of the promising classes of chemotherapeutic agents for cancer treatment. The main deterrent to their use is high toxicity to a healthy environment, including cumulative cardiotoxicity. In our work, bipharmacophore molecules containing in their structure a fragment of the known anthracycline antibiotics daunorubicin and doxorubicin and natural sesquiterpene lactones were obtained for the first time. When studying the biological activity of the synthesized compounds, it was found that with equal and, in some cases, higher cytotoxicity and glycolysis inhibition by anthracycline antibiotics conjugates with sesquiterpene lactones in comparison with doxo- and daunorubicin, a reduced damaging effect on the functioning of rat heart mitochondria was observed. The results obtained allow us to confirm the assumption that the chemical modification of the anthracycline antibiotics molecules doxo- and daunorubicin by natural sesquiterpene lactones can be a promising strategy for creating potential antitumor chemotherapeutic drugs with a pronounced cytotoxic effect on tumor cells and a reduced damaging effect on healthy cells of the human organism.

Multiple Mechanisms Regulate Eukaryotic Cytochrome C Oxidase

Cytochrome c oxidase (COX), the rate-limiting enzyme of mitochondrial respiration, is regulated by various mechanisms. Its regulation by ATP (adenosine triphosphate) appears of particular importance, since it evolved early during evolution and is still found in cyanobacteria, but not in other bacteria. Therefore the “allosteric ATP inhibition of COX” is described here in more detail. Most regulatory properties of COX are related to “supernumerary” subunits, which are largely absent in bacterial COX. The “allosteric ATP inhibition of COX” was also recently described in intact isolated rat heart mitochondria.

Celecoxib Decreases Mitochondrial Complex IV Activity and Induces Oxidative Stress in Isolated Rat Heart Mitochondria: An Analysis for its Cardiotoxic Adverse Effect

Background In spite of the cardiotoxic effect of selective cyclooxygenase-2 inhibitors, they are most widely used as anti-inflammatory and analgesic drugs. Today, valdecoxib and rofecoxib have been withdrawn on the market but celecoxib remains. In this study, we focused on an analysis of celecoxib toxic effects on isolated mitochondrial. Methods isolated rat heart mitochondria were obtained using differential centrifugation. Using flowcytometry and biochemical assays we searched succinate dehydrogenases (SDH), mitochondrial membrane potential (MMP), reactive oxygen species (ROS) formation, mitochondrial swelling, lipid peroxidation and mitochondrial complexes activity in rat heart isolated mitochondria. Results In here our results indicated a significant decrease in activity of complexes IV after exposure with celecoxib (16 µg/ml). This decrease in activity of complexes IV is paralleled by the MMP collapse, ROS formation, mitochondrial swelling and lipid peroxidation. Conclusion For the first time, this introductory study has showed a significant decrease in activity of complexes IV and mitochondrial dysfunction after exposure with celecoxib in rat heart isolated mitochondria.

Isoproterenol-Induced Permeability Transition Pore-Related Dysfunction of Heart Mitochondria Is Attenuated by Astaxanthin

Mitochondria are key organelles of the cell because their main function is the capture of energy-rich substrates from the cytoplasm and oxidative cleavage with the generation of carbon dioxide and water, processes that are coupled with the synthesis of ATP. Mitochondria are subject to oxidative stress through the formation of the mitochondrial permeability transition pore (mPTP). Various antioxidants are used to reduce damage caused by oxidative stress and to improve the protection of the antioxidant system. Astaxanthin (AST) is considered to be a dietary antioxidant, which is able to reduce oxidative stress and enhance the antioxidant defense system. In the present investigation, the effect of AST on the functional state of rat heart mitochondria impaired by isoproterenol (ISO) under mPTP functioning was examined. It was found that AST raised mitochondrial respiration, the Ca2+ retention capacity (CRC), and the rate of TPP+ influx in rat heart mitochondria (RHM) isolated from ISO-injected rats. However, the level of reactive oxygen species (ROS) production increased. In addition, the concentrations of cardiolipin (CL), Mn-SOD2, and the proteins regulating mPTP rose after the injection of ISO in RHM pretreated with AST. Based on the data obtained, we suggest that AST has a protective effect in rat heart mitochondria.