16 research outputs found
A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction
Background: Carbohydrates play a major role in cell signaling in many biological processes. We have developed a set of glycomimetic drugs that mimic the structure of carbohydrates and represent a novel source of therapeutics for endothelial dysfunction, a key initiating factor in cardiovascular complications. Purpose: Our objective was to determine the protective effects of small molecule glycomimetics against free fatty acidinduced endothelial dysfunction, focusing on nitric oxide (NO) and oxidative stress pathways. Methods: Four glycomimetics were synthesized by the stepwise transformation of 2,5dihydroxybenzoic acid to a range of 2,5substituted benzoic acid derivatives, incorporating the key sulfate groups to mimic the interactions of heparan sulfate. Endothelial function was assessed using acetylcholineinduced, endotheliumdependent relaxation in mouse thoracic aortic rings using wire myography. Human umbilical vein endothelial cell (HUVEC) behavior was evaluated in the presence or absence of the free fatty acid, palmitate, with or without glycomimetics (1µM). DAF2 and H2DCFDA assays were used to determine nitric oxide (NO) and reactive oxygen species (ROS) production, respectively. Lipid peroxidation colorimetric and antioxidant enzyme activity assays were also carried out. RTPCR and western blotting were utilized to measure Akt, eNOS, Nrf2, NQO1 and HO1 expression. Results: Ex vivo endotheliumdependent relaxation was significantly improved by the glycomimetics under palmitateinduced oxidative stress. In vitro studies showed that the glycomimetics protected HUVECs against the palmitateinduced oxidative stress and enhanced NO production. We demonstrate that the protective effects of preincubation with glycomimetics occurred via upregulation of Akt/eNOS signaling, activation of the Nrf2/ARE pathway, and suppression of ROSinduced lipid peroxidation. Conclusion: We have developed a novel set of small molecule glycomimetics that protect against free fatty acidinduced endothelial dysfunction and thus, represent a new category of therapeutic drugs to target endothelial damage, the first line of defense against cardiovascular disease
Estimation of ATP-dependent K(+)-channel contribution to potential-dependent potassium uptake in the rat brain mitochondria
The effect of potassium on state 4 respiration (substrate oxidation in the absence of ADP) was investigated. It was shown that potential-dependent potassium uptake in the brain mitochondria results in mitochondrial depolarization. Taking into account depolarization effect of potassium, the contribution of the endogenous proton leak as well as K+-uptake to the respiration rate was calculated. It was shown that such estimation allows the share of ATP-dependent potassium channel contribution to potential-dependent potassium uptake to be determined by polarographic method
The effect of ATP-dependent K(+)-channel opener on the functional state and the opening of cyclosporine-sensitive pore in rat liver mitochondria
The effect of mitochondrial ATP-dependent K+-channel (K+АТР-channel) opener diazoxide (DZ) on the oxygen consumption, functional state and the opening of cyclosporine-sensitive pore in the rat liver mitochondria has been studied. It has been established that K+АТР-channel activation results in the increase of the oxygen consumption rate (V4S) and the uncoupling due to the acceleration of K+-cycling, the decrease in state 3 respiration rate (V3) and the respiratory control ratio (RCR). Under K+АТР-channel activation an inhibition of oxidative phosphorylation takes place which reduces the rate of ATP synthesis and hydrolysis as well as ATP production and consequently results in the seeming increase of P/O ratio. It has been shown that the increase in ATP-dependent K+-uptake accompanied by the opening of mitochondrial permeability transition pore (MPTP) leads to dramatic uncoupling of the respiratory chain due to simultaneous activation of K+– and Ca2+-cycling supported by MPTP and Ca2+-uniporter as well as K+-channels and K+/H+-exchange. K+АТР-channel activation leads to the partial inhibition of MPTP, but insufficient for the restoration of mitochondrial functions. Elimination of Ca2+-cycling after MPTP opening is necessary to return mitochondrial functions back to the control level which shows that MPTP could serve as the mechanism of reversible modulation of bioenergetic effects of K+АТР-channel activation
The effect of potential-dependent potassium uptake on membrane potential in rat brain mitochondria
The effect of potential-dependent potassium uptake on the transmembrane potential difference (ΔΨm) in rat brain mitochondria has been studied. It was shown that in potassium concentration range of 0-120 mM the potential-dependent K+-uptake into matrix leads to the increase in respiration rate and mitochondrial depolarization. ATP-dependent potassium channel (K+ATP-channel) blockers, glibenclamide and 5-hydroxydecanoate, block ~35% of potential-dependent potassium uptake in the brain mitochondria. It was shown that K+ATP-channel blockage results in membrane repolarization by ~20% of control, which is consistent with experimental dependence of ΔΨm on the rate of potential-dependent potassium uptake. Obtained experimental data give the evidence that functional activity of K+ATP-channel is physiologically important in the regulation of membrane potential and energy-dependent processes in brain mitochondria
The effect of ATP-dependent K(+)-channel opener on transmembrane potassium exchange and reactive oxygen species production upon the opening of mitochondrial pore
The effect of mitochondrial ATP-dependent K+-channel (K+ATP-channel) opener diazoxide (DZ) on transmembrane potassium exchange and reactive oxygen species (ROS) formation under the opening of mitochondrial permeability transition pore (MPTP) was studied in rat liver mitochondria. The activation of K+-cycling (K+-uptake and K+/H+-exchange) by DZ was established with peak effect at ≤500 nM. It was shown that MPTP opening as well resulted in the activation of K+-cycling together with simultaneous activation of Ca2+-cycle in mitochondria. In the absence of depolarization Ca2+-cycle is supported by MPTP and Ca2+-uniporter. The stimulation of K+/H+-exchange by MPTP opening led to the activation of K+-cycle, but further activation of K+/H+-exchange resulted in MPTP inhibition. Under the same conditions the decrease in mitochondrial ROS production was observed. It was proposed that the decrease in ROS formation together with K+/Н+-exchange activation could be the constituents of the complex effect of MPTP inhibition induced by K+ATP-channel opener