Modulation of the Activity of Succinate Dehydrogenase by Acetylation with Chemicals,Drugs, and Microbial Metabolites

Biophysics - Abstract—The effects of acetylating and deacetylating compounds on the activity of succinate dehydrogenase, as well as on the membrane potential and calcium retention capacity of...     

Amaranth seed oil: Effect of oral administration on energetic functions of rat liver mitochondria activated with adrenaline

Respiration parameters of liver mitochondria (MCh) in rats fed with amaranth seed oil for 3 weeks have been evaluated. Thirty minutes before decapitation, adrenaline was injected intraperitoneally at a low dose (350 μg/kg body weight) to both control and experimental animals. It was shown that in animals that were injected with adrenaline and did not receive oil, the rate of phosphorylating respiration increased by 32% and phosphorylation time decreased by 22% upon oxidation of succinate; upon oxidation of α-ketoglutarate in the presence of the succinate dehydrogenase inhibitor malonate, phosphorylating respiration was activated by 23%. The respiration of MCh upon oxidation of succinate + glutamate and α-ketoglutarate in the absence of malonate was not affected by adrenaline. The intake of oil markedly activated almost all parameters of mitochondrial respiration in experimental rats upon oxidation of all above-listed substrates in both coupled and uncoupled MCh. However, phosphorylation time was close to the control value (upon oxidation of succinate) or increased (upon oxidation of α-ketoglutarate in the presence and absence of malonate). The injection of adrenaline to animals receiving oil did not affect the oil-activated respiration of MCh oxidizing the substrates used; however, phosphorylation time in all groups of animals decreased. Ca²⁺ capacity of MCh in rats receiving amaranth oil did not change. Thus, our data show that feeding of rats with amaranth oil activates mitochondrial respiration and prevents MCh hyperactivation induced by adrenaline.     

Preservation of the in vivo state of mitochondrial network for ex vivo physiological study of mitochondria

Over the course of many years our laboratory has been engaged in the study of physiological functions of mitochondria ex vivo.We showed that the unavoidable destruction of mitochondrial-reticular network during traditional isolation of the mitochondria diminishes the observable ex vivo changes of mitochondrial processes in vivo. Comparing preparations obtained from quiescent and stressed rats, we found that the great difference in size of assemblies of mitochondria preserved in homogenate disappears when it is diluted for the measurement of respiration. This also leads to a decrease in the difference between respiration of mitochondria from quiescent and stressed animals.We developed a new method that provides ex vivo stable preservation of the in vivo network using a cytochemical procedure on glass-adhered lymphocytes in blood smear. We radically changed the incubation medium for the measurement of dehydrogenase activity that excludes an artefact of succinate dehydrogenase hyperactivation ex vivo by non-physiological components of the traditionally used solution. Our method made it possible to observe ex vivo two- to eightfold increase in succinate dehydrogenase activity by adrenaline in vivo, while the activity of α-ketoglutarate dehydrogenase changed reciprocally.The data obtained show that the structure changes of the network play an important role in physiological regulation of mitochondrial functions. Thus, it may be possible to correct mitochondrial dysfunctions in the organism by substances supporting the stability of mitochondrial network. The developed method is non-invasive, informative and, therefore, is convenient for clinical investigations, particularly of mitochondrial diseases.     

The effect of cell-phone radiation on rabbits: Lymphocyte enzyme-activity data

The effect of a GSM 900/1800 mobile phone, which is a widespread source of electromagnetic radiation of the microwave frequency in the environment, on rabbits was studied at power densities of 5–7 μW/cm². The biological effect was recorded by a sensitive method for the detection of the physiological regulation of enzyme activity inside lymphocytes in blood smears. Succinate dehydrogenase, which is the most powerful energy-supply enzyme in mitochondria, and lactate dehydrogenase, which is an enzyme of glycolysis, were measured. The lactate dehydrogenase to succinate dehydrogenase activity ratio was also calculated as an analog of the Warburg effect, which demonstrates the relationship between glycolysis and respiration. After 60 min of mobile-phone exposure each day for 11 days at a moderate dose, the emitted radiation induced a threefold increase in succinate dehydrogenase activity and a twofold decrease in lactate dehydrogenase activity. As a result, the lactate dehydrogenase/succinate dehydrogenase activity ratio falls from 15 to 5, thus indicating that respiration is predominant over glycolysis. The changes develop already after the first exposure and reach a maximum in 4 days. The predominance of respiration is usually considered as a beneficial state of an organism. However, continuous activation of respiration by mobile phone exposure may cause damage to the normal restorative processes that are supported by glycolysis during periods of rest.     

Hyperactivation of succinate dehydrogenase in lymphocytes of newborn rats

We measured the activity of mitochondrial succinate dehydrogenase (SDH) within cells, in media with near-physiological composition, in lymphocytes immobilized in a blood smear on glass. SDH activity was studied in newborn rats characterized by natural hyperadrenergic status and also in adult animals injected with epinephrine. In most newborns very high activities were recorded, which exceeded the activities in adults at rest 7-8-fold or 3-fold according to the conventional calculation, or more than 30- and 6-fold according to our more precise calculation. The findings support our concept about a selective interaction between adrenergic stimulation and oxidation of succinic acid. According to this concept, epinephrine and norepinephrine specifically activate oxidation of succinic acid, whereas blood micromolar concentrations of the latter stimulate the release of catecholamines (the receptor-mediated signaling effect). This interaction is half of a substrate-hormonal regulatory system responsible for connection of vegetative nervous system with oxidation in mitochondria of the innervated organs. The increase in succinate oxidation by catecholamines includes activation of the faster pathways of succinate generation than the complete Krebs cycle, in particular, the glyoxylate cycle that is shown in the newborn rats in the present study.     

Role of the impairment of oxidative metabolism in pathogenesis of lower urinary tract symptoms with benign prostatic hyperplasia and their treatment by alpha1-adrenoblocker alfuzosin

The role of impairment of general oxidative and energy metabolism in pathogenesis of lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH) and their correction by (1-adrenoblocker alfuzosin was studied. One group of patients (N = 126) was examined by standard methods for determination of the severity of LUTS by IPSS and mean effective volume of urinary bladder (MEVUB). In the second group (N = 29) in addition to functional examinations, metabolic indicators in blood were measured: antioxidant activity (AOA) and succinate dehydrogenase activity (SDA). Severity of LUTS depends greatly on the MEVUB. It was the first to show a practically complete correlation between LUTS, AOA and SDA. Severity of LUTS exactly correlates with indicators of oxidative and energy metabolism. In patients with more heavy LUTS, lowest AOA and SDA values were found. In the course of effective treatment, both phenomena developed an improvement of clinical symptoms and a rise of biochemical parameters. Close correlation between functional and metabolic phenomena is evidence of an essential role of metabolic mechanisms in the pathogenesis of LUTS with BPH. This opens perspectives to use antioxidants and energy metabolism activators for correction of UB dysfunction in patients with BPH.     

The effects of near infrared radiation on rats assessed by succinate dehydrogenase activity in lymphocytes in blood smears

The biological effects of near infrared radiation (850 nm) modulated by an acoustic frequency of 101 Hz were studied. The study was conducted on rats; the effect was registered by succinate dehydrogenase activity in lymphocytes in blood smears after the administration of an activating dose of adrenaline, which simulates the state of the organism at early stages of a pathogenic action (stress). A pronounced regulating effect of infrared radiation on the activity of succinate dehydrogenase in animals that were activated by adrenaline was shown. Infrared radiation has a normalizing effect via the reduction of the degree of inhibition or activation of the enzyme induced by adrenaline and has no effect on the control animals. Thus, by modulation of the activity of succinate dehydrogenase, infrared radiation regulates energy production in mitochondria that is provided by the most potent oxidation substrate, viz., succinic acid; the effect is especially pronounced under stress.     

States of succinate dehydrogenase in the organism: Dormant vs. hyperactive (pushed out of equilibrium)

Using an original cytobiochemical method to study oxidation in mitochondria, preserving their native network organization within cells in a blood smear, we have revealed a hyperactive state of succinate dehydrogenase that arises in the organism under physiological stress. This is generally consistent with the notion of non-equilibrium state of enzymes during their activity. The mechanism moderating the succinate dehydrogenase hyperactivity is based on full-fledged functioning of α-ketoglutarate dehydrogenase, sup-ported by oxidation of isocitrate.     

Importance of preserving the biophysical organization of isolated mitochondria for revealing their physiological regulation

A method has been elaborated that preserves the mitochondrial-reticular network in lymphocytes by immobilization of a blood smear on glass and its subsequent incubation in a medium close in composition to the physiological one. Physiological responses of mitochondrial respiration to excitation in the organism are well pronounced on these preparations. Detection of early responses of mitochondria to pathogenic agents in the organism is a topical problem of basic and medical research, since such alterations play a leading role in the development of pathological states.