Biomedical subjects

Adolfas Toleikis

Publications and source records attributed to Adolfas Toleikis.

6 recordsLinked to original sources

PubMed2006

A user-friendly PC-based data acquisition and analysis system for respirometric investigations.

We have developed an easy-to-use computer-based system for recording, displaying, storing and analyzing signals generated by Clark-type oxygen electrodes. A user-friendly interface of Windows-based program BioMed significantly increases the productivity of investigations. It allows to process, control, present and archive the experimental data in real time. A 12-bit analog-to-digital-converter, analog and digital filters, a possibility to zoom the obtained respiratory curves and calculation of the respiration rates by a linear regression method increase the resolution of the estimated oxygen consumption rates. The new system enables to register even small changes, such as 3-5 ngatoms O/min, in respiration rates of biological objects -- enzymes, mitochondria and permeabilized muscle fibers. The system has been developed and is regularly used for the respirometric investigations at the Laboratory of Biochemistry, Institute for Biomedical Research, Kaunas University of Medicine.

Analog-Digital Conversion↗

PubMed2006

Influence of propolis water solution on heart mitochondrial function.

The effect of propolis water solution (PWS) on the respiration of rat heart mitochondria with NAD-linked (pyruvate + malate), FAD-linked (succinate) substrates and fatty acids (palmitoyl-L-carnitine) was investigated in this study. PWS at the lowest concentration of 4 microg mL(-1) of phenolic compounds (PC) had no effect on mitochondrial respiration with all investigated substrates. PWS at concentrations of 63 and 125 microg mL(-1) of PC caused a significant decrease of basal (24 and 54%) and maximal (58 and 70%) respiration rates with succinate as substrate. At these PWS concentrations the oxidation of pyruvate + malate and palmitoyl-L-carnitine was diminished to a lower degree: the basal respiration rate decreased by 13-18% and the maximal respiration rate by 15-28%. Succinate oxidation was affected, probably because of the inhibition of succinate dehydrogenase by the 1,2-benzenedicarboxylic acid esters found in PWS. The PWS-caused decrease in the mitochondrial respiration rate with pyruvate + malate and fatty acids could be due to diminished activities of respiratory chain complexes and/or ADP/ATP translocator.

Animals↗

PubMed2005

Myocardial protective effect of warm blood, tepid blood, and cold crystalloid cardioplegia in coronary artery bypass grafting surgery.

AIM: To compare the myocardial effects of cardioplegia by warm blood, tepid blood, and cold crystalloid during coronary artery bypass grafting (CABG). METHODS: Patients undergoing CABG surgery at Kaunas University Hospital between 2000 and 2004 were randomized into three groups (n=156), receiving a different method of cardioplegia. Intermittent antegrade warm blood cardioplegia was used in 51 patients, tepid blood cardioplegia in 50 patients, and cold crystalloid cardioplegia in 55 patients. Mitochondrial function, myocardial ultrastructure, troponin T, and hemodynamic and clinical data were analyzed after surgery. RESULTS: All cardioplegic methods similarly affected structural and functional properties of mitochondria and coupling of oxidative phosphorylation, and all lowered the capacity of mitochondria to synthesize ATP. Ultrastructure of myocytes showed slight to moderate injury in the cold crystalloid cardioplegia group. The concentration of troponin T was significantly lower in the warm blood cardioplegia group than in the tepid blood cardioplegia and cold crystalloid cardioplegia groups at 12 hours (0.8+/-0.1 ng/mL, 1.9+/-0.2 ng/mL, and 2.8+/-0.3 ng/mL, respectively; P<0.001) and 24 hours after surgery (1.0+/-0.1 ng/mL, 2.2+/-0.3 ng/mL, and 2.5+/-0.3 ng/mL, respectively; P<0.001). Echocardiographic examination after surgery revealed that the changes in the left ventricle diastolic function were similar in all groups, and that systolic function did not change. The warm blood cardioplegia group showed shorter duration of intubation and hospitalization. There were no differences in the need of catecholamine administration, incidence of complications, and duration of stay in the intensive care unit. CONCLUSIONS: Intermittent antegrade warm blood cardioplegia provides better myocardial protection during CABG surgery, as assessed by the lower release of troponin T, lower fluid balance, shorter duration of tracheal intubation and hospital stay.

Body Temperature↗

PubMed2003

Adenine nucleotide translocase mediates the K(ATP)-channel-openers-induced proton and potassium flux to the mitochondrial matrix.

KATP channel openers have been shown to protect ischemic-reperfused myocardium by mimicking ischemic preconditioning, although their mechanisms of action have not been fully clarified. In this study we investigated the influence of the adenine nucleotide translocase (ANT) inhibitors--carboxyatractyloside (CAT) and bongkrekic acid (BA)--on the diazoxide- and pinacidil-induced uncoupling of isolated rat heart mitochondria respiring on pyruvate and malate (6 + 6 mM). We found that both CAT (1.3 microM) and BA (20 microM) markedly reduced the uncoupling of mitochondrial oxidative phosphorylation induced by the K(ATP) channel openers. Thus, the uncoupling effect of diazoxide and pinacidil is evident only when ANT is not fixed by inhibitors in neither the C- nor the M-conformation. Moreover, the uncoupling effect of diazoxide and pinacidil was diminished in the presence of ADP or ATP, indicating a competition of K(ATP) channel openers with adenine nucleotides. CAT also abolished K+-dependent mitochondrial respiratory changes. Thus ANT could also be involved in the regulation of K(ATP)-channel-openers-induced K+ flux through the inner mitochondrial membrane.

Animals↗

PubMed2002

Diazoxide and pinacidil uncouple pyruvate-malate-induced mitochondrial respiration.

We investigated the effects of K(ATP) channel openers diazoxide and pinacidil on the respiration rate and membrane potential (deltapsi) of rat heart mitochondria, oxidizing pyruvate and malate. Diazoxide and pinacidil (58.8-1348.3 microM) increased the V2 (-ADP) respiration rate accordingly by 13-208% and 30-273% and decreased the deltapsi by 2-17% and 6-55%. These effects were also similar in the respiration medium without K+. Moreover, carboxyatractyloside completely abolished diazoxide- and pinacidil-induced uncoupling, indicating a role for the mitochondrial adenine nucleotide translocase in this process.

Animals↗

PubMedDate not supplied

Cytochrome C effect on respiration of heart mitochondria: influence of various factors.

The effect of exogenous cytochrome c on respiration rate of the rat and human heart mitochondria was assessed in situ, using permeabilized fibers. It was (i) much more pronounced in State 2 and 4 than in State 3 with all the respiratory substrates (pyruvate+malate, succinate, palmitoyl-CoA+carnitine and octanoyl-L-carnitine), (ii) different with different substrates, (iii) much higher after ischemia in both metabolic states, particularly in the case of succinate oxidation compared to pyruvate+malate, (iv) the highest in State 4 with succinate as a substrate. Similar results were obtained with the isolated rat and rabbit heart mitochondria. The differences in the degree of stimulation of mitochondrial respiration by cytochrome c and, thus, sensitivity of cytochrome c test in evaluation of the intactness/injury of outer mitochondrial membrane are probably determined by the differences in the cytochrome c role in the control of mitochondrial respiration in the above-described conditions.

Animals↗