Few studies have investigated the hemodynamic mechanism whereby primary hyperaldosteronism causes hypertension. The traditional view holds that hyperaldosteronism initiates hypertension by amplifying salt-dependent increases in cardiac output (CO) by promoting increases in sodium retention and blood volume. Systemic vascular resistance (SVR) is said to increase only as a secondary consequence of the increased CO and blood pressure. Recently, we investigated the primary hemodynamic mechanism whereby hyperaldosteronism promotes salt sensitivity and initiation of salt-dependent hypertension. In unilaterally nephrectomized male Sprague-Dawley rats given infusions of aldosterone or vehicle, we found that aldosterone promoted salt sensitivity and initiation of salt-dependent hypertension by amplifying salt-induced increases in SVR while decreasing CO. In addition, we validated mathematical models of human integrative physiology, derived from Guyton's classic 1972 model - Quantitative Cardiovascular Physiology-2005 and HumMod-3.0.4. Neither model accurately predicted the usual changes in sodium balance, CO, and SVR that normally occur in response to clinically realistic increases in salt intake. These results demonstrate significant limitations with the hypotheses inherent in the Guyton models. Together these findings challenge the traditional view of the hemodynamic mechanisms that cause salt-sensitive hypertension in primary aldosteronism. Key words: Aldosterone, Blood pressure, Salt, Sodium, Rat.
- Publikační typ
- časopisecké články MeSH
Lysosomes, now known to take part in multiple cellular functions, also respond to various stress stimuli. These include biogenesis in response to nanomolar concentrations of hydrophobic weak-base anticancer drugs. However, since lysosomal stress mediated by accumulation of weak-base drugs at such concentrations has never been proven and these drugs have diverse effects on malignant cells, we investigated whether the interpretation of the data was true. We found that lysosomal accumulation of the drugs daunorubicin, doxorubicin, mitoxantrone, symadex, chloroquine, clomipramine and sunitinib alone, was insufficient to induce lysosomal alkalization i.e., lysosomal stress-mediated biogenesis at nanomolar concentrations. Instead, we found that some of the drugs used induced G2 phase arrest and lysosomal biogenesis that is associated with activation of transcription factor EB (TFEB). Similarly, cantharidin, a control compound that does not belong to the weak base drugs, induced cell cycle arrest in the G2 phase associated with TFEB-driven lysosomal biogenesis. Overall none of the tested drugs caused stress-induced lysosomal biogenesis at nanomolar concentrations. However, daunorubicin, doxorubicin, mitoxantrone, symadex and cantharidin induced a massive block in the G2 phase of the cell cycle which is naturally associated with TFEB-driven lysosomal biogenesis.
- Klíčová slova
- A549 cells, Cell cycle progression, G2 arrest, K562 cells, Lysosomal biogenesis, Lysosomal sequestration, Weak base drugs,
- MeSH
- autofagie MeSH
- buněčný cyklus MeSH
- doxorubicin metabolismus farmakologie MeSH
- kantharidin * MeSH
- lyzozomy metabolismus MeSH
- mitoxantron * farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- doxorubicin MeSH
- kantharidin * MeSH
- mitoxantron * MeSH
Mitochondrial retrograde signaling is a pathway of communication from mitochondria to the nucleus. Recently, natural mitochondrial genome (mtDNA) polymorphisms (haplogroups) received increasing attention in the pathophysiology of human common diseases. However, retrograde effects of mtDNA variants on such traits are difficult to study in humans. The conplastic strains represent key animal models to elucidate regulatory roles of mtDNA haplogroups on defined nuclear genome background. To analyze the relationship between mtDNA variants and cardiometabolic traits, we derived a set of rat conplastic strains (SHR-mtBN, SHR-mtF344 and SHR-mtLEW), harboring all major mtDNA haplotypes present in common inbred strains on the nuclear background of the spontaneously hypertensive rat (SHR). The BN, F344 and LEW mtDNA differ from the SHR in multiple amino acid substitutions in protein coding genes and also in variants of tRNA and rRNA genes. Different mtDNA haplotypes were found to predispose to various sets of cardiometabolic phenotypes which provided evidence for significant retrograde effects of mtDNA in the SHR. In the future, these animals could be used to decipher individual biochemical components involved in the retrograde signaling.
- MeSH
- fenotyp MeSH
- kardiovaskulární nemoci * metabolismus MeSH
- krysa rodu Rattus MeSH
- mitochondriální DNA * genetika MeSH
- mitochondrie metabolismus MeSH
- potkani inbrední F344 MeSH
- potkani inbrední SHR MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- přehledy MeSH
- Názvy látek
- mitochondriální DNA * MeSH
Increased plasma total cysteine (tCys) has been associated with obesity and metabolic syndrome in human and some animal studies but the underlying mechanisms remain unclear. In this study, we aimed at evaluating the effects of high cysteine diet administered to SHR-CRP transgenic rats, a model of metabolic syndrome and inflammation. SHR-CRP rats were fed either standard (3.2 g cystine/kg diet) or high cysteine diet (HCD, enriched with additional 4 g L-cysteine/kg diet). After 4 weeks, urine, plasma and tissue samples were collected and parameters of metabolic syndrome, sulfur metabolites and hepatic gene expression were evaluated. Rats on HCD exhibited similar body weights and weights of fat depots, reduced levels of serum insulin, and reduced oxidative stress in the liver. The HCD did not change concentrations of tCys in tissues and body fluids while taurine in tissues and body fluids, and urinary sulfate were significantly increased. In contrast, betaine levels were significantly reduced possibly compensating for taurine elevation. In summary, increased Cys intake did not induce obesity while it ameliorated insulin resistance in the SHR-CRP rats, possibly due to beneficial effects of accumulating taurine.
- MeSH
- adipozita * MeSH
- cystein metabolismus farmakologie MeSH
- inzulinová rezistence * MeSH
- krysa rodu Rattus MeSH
- metabolismus lipidů MeSH
- potkani inbrední SHR MeSH
- potkani transgenní MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cystein MeSH
Lysosomal sequestration of weak base drugs has been identified as one of the stress-related mechanisms that trigger in vitro lysosomal biogenesis controlled by transcription factor EB (TFEB). Whether such mechanism can induce lysosomal biogenesis in vivo is unknown. In this study, we addressed the question whether prolonged treatment with sunitinib (SUN) in patients with advanced renal cell carcinoma (n = 22) and with imatinib (IM) in those with gastrointestinal stromal tumor (n = 6) could induce lysosomal biogenesis in leukocytes. Lysosomal biogenesis was monitored using immunoblotting of three lysosomal membrane proteins: lysosome-associated membrane proteins 1 and 2 (LAMP1 and LAMP2) and vacuolar H+-ATPase, B2 subunit (ATP6V1B2). Present results indicate that prolonged treatment with SUN affects LAMP1 and LAMP2 expression only marginally in most patients. In contrast, changes in ATP6V1B2 expression were marked and resembled irregular oscillations. Very similar changes in the expression of lysosomal membrane proteins were also found in IM-treated patients. Conclusion: prolonged treatment of cancer patients with SUN and IM did not induce leucocyte lysosomal biogenesis but dramatically affected expression of ATP6V1B2.
- Klíčová slova
- B2 subunit, Imatinib, LAMP1, LAMP2, Lysosmal membrane proteins, Sunitinib, Vacuolar H+-ATPase,
- MeSH
- gastrointestinální stromální tumory farmakoterapie metabolismus MeSH
- imatinib mesylát terapeutické užití MeSH
- inhibitory proteinkinas terapeutické užití MeSH
- karcinom z renálních buněk farmakoterapie metabolismus MeSH
- leukocyty metabolismus MeSH
- lidé MeSH
- lyzozomy metabolismus MeSH
- membránové glykoproteiny asociované s lyzozomy metabolismus MeSH
- sunitinib terapeutické užití MeSH
- transkripční faktory BHLH-Zip metabolismus MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- imatinib mesylát MeSH
- inhibitory proteinkinas MeSH
- membránové glykoproteiny asociované s lyzozomy MeSH
- sunitinib MeSH
- transkripční faktory BHLH-Zip MeSH
Altered intracellular distribution of weak base anticancer drugs owing to lysosomal sequestration is one purported mechanism contributing to chemotherapy resistance. This has often been demonstrated with the example of daunorubicin (DNR), chemotherapy with its characteristic red fluorescence used to trace it in cellular compartments. Here we addressed the question whether image analysis of DNR fluorescence can reflect its real intracellular distribution. We observed that the relationship between the intensity of the DNR fluorescence and its concentration in water solutions with or without proteins is far from linear. In contrast, nucleic acids, RNA and DNA in particular, dramatically diminish the DNR fluorescence, however, the intensity was proportional to the amount. Therefore, image analysis reflects the composition of different cell compartments (i.e., the presence of proteins and nucleic acids) rather than the actual concentration of DNR in these compartments. In line with these results, we observed highly fluorescent lysosomes and low fluorescent nucleus in sensitive cancer cells treated with low DNR concentrations, a fluorescence pattern thought to be found only in resistant cancer cells. Importantly, LC/MS/MS analysis of extracts from sensitive cells treated with DNR or DNR in combination with an inhibitor of vacuolar ATPase, concanamycin A, indicated that lysosomal accumulation of DNR increased with increasing extracellular concentration. However, even the highest lysosomal accumulation of DNR failed to reduce its extralysosomal concentration and thus change the cell sensitivity to the drug. In conclusion, our results strongly suggest that DNR fluorescence within cells does not indicate the real drug distribution. Further they suggested that lysosomal sequestration of DNR can hardly contribute to its resistance in cancer cells in vitro.
- Klíčová slova
- Daunomycin, Drug resistance, HT-29 cells, K562 cells, Lysosomal sequestration, image Analysis,
- MeSH
- chemorezistence účinky léků MeSH
- chromatografie kapalinová MeSH
- daunomycin analýza farmakokinetika MeSH
- fluorescenční mikroskopie MeSH
- inhibitory enzymů farmakologie MeSH
- lidé MeSH
- lyzozomy metabolismus MeSH
- nádorové buněčné linie MeSH
- tandemová hmotnostní spektrometrie MeSH
- vakuolární protonové ATPasy antagonisté a inhibitory MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- daunomycin MeSH
- inhibitory enzymů MeSH
- vakuolární protonové ATPasy MeSH
Although cadmium (Cd2+) is unable to form reactive oxygen species (ROS) directly, many of its adverse effects are connected to increased ROS generation resulting in cell death. In support of this supposition, a large number of studies have shown protective effects of antioxidants such as N-acetylcysteine (NAC) against cadmium induced cytotoxicity. Here, we describe the cytotoxic effects of Cd2+ on human leukemia U937 and K562 cells that were not mediated by oxidative stress. Surprisingly, we observed that addition of low concentrations of NAC can drastically potentiate cadmium cytotoxicity solely via ROS production. However, all adverse effects of the metal were prevented by NAC at high concentrations. Detailed analysis indicated that the protective effect of NAC was mediated by its ability to form stable complex with cadmium [Cd(NAC)2]. In conclusion, NAC exhibits dual and antagonistic effects on Cd2+ cytotoxicity in human leukemia cells.
- Klíčová slova
- Cadmium chelation, Cadmium cytotoxicity, K562 cells, N-acetylcysteine, Reactive oxygen species, U937 cells,
- MeSH
- acetylcystein farmakologie MeSH
- buňky K562 MeSH
- chelátory farmakologie MeSH
- kadmium toxicita MeSH
- látky znečišťující životní prostředí toxicita MeSH
- lidé MeSH
- reaktivní formy kyslíku metabolismus MeSH
- U937 buňky MeSH
- viabilita buněk účinky léků MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- acetylcystein MeSH
- chelátory MeSH
- kadmium MeSH
- látky znečišťující životní prostředí MeSH
- reaktivní formy kyslíku MeSH
Etoposide is a well-known and widely used anticancer drug that displays several side effects. In addition, tumors often acquire resistance to this drug. Our aim is to develop a combination therapy that would augment toxicity of etoposide in malignant cells. Based on literature and our experiments, we selected mifepristone (RU486) as a potential supporting molecule that is able to enhance etoposide toxicity against cancer cells. All experiments were performed with Hep G2 cells, a well-known and described human hepatocellular carcinoma cell line. By using xCELLigence system, we demonstrated that mifepristone enhances toxicity of etoposide in a dose dependent manner with concomitant caspase-3 activity. We evaluated upregulation of Bax because mifepristone was demonstrated to modulate proapoptotic Bax protein expression. Our data show only weak and not statistically significant increase of Bax expression. On the other hand, we show that mifepristone increases etoposide toxicity via inhibition of ABC transporters, coupled with significant increase of intracellular etoposide concentration. In conclusion, we demonstrate that mifepristone has a synergistic effect with etoposide treatment in the Hep G2 cells and that the effect is related to ABC transporters inhibition.
- Klíčová slova
- ABC transporters, Etoposide, Hep G2 cells, RU486, xCELLigence,
- MeSH
- ABC transportér z rodiny G, člen 2 antagonisté a inhibitory MeSH
- antitumorózní látky fytogenní farmakologie MeSH
- biologický transport účinky léků MeSH
- buňky Hep G2 MeSH
- buňky K562 MeSH
- etoposid farmakologie MeSH
- kaspasa 3 metabolismus MeSH
- lidé MeSH
- mifepriston farmakologie MeSH
- nádorové proteiny antagonisté a inhibitory MeSH
- P-glykoproteiny antagonisté a inhibitory MeSH
- protein X asociovaný s bcl-2 metabolismus MeSH
- synergismus léků MeSH
- viabilita buněk účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ABC transportér z rodiny G, člen 2 MeSH
- ABCB1 protein, human MeSH Prohlížeč
- ABCG2 protein, human MeSH Prohlížeč
- antitumorózní látky fytogenní MeSH
- BAX protein, human MeSH Prohlížeč
- CASP3 protein, human MeSH Prohlížeč
- etoposid MeSH
- kaspasa 3 MeSH
- mifepriston MeSH
- nádorové proteiny MeSH
- P-glykoproteiny MeSH
- protein X asociovaný s bcl-2 MeSH
Telmisartan is an angiotensin receptor blocker (ARB) and a selective peroxisome proliferator activated receptor gamma (PPARG) modulator. Recently, we tested metabolic effects of telmisartan (5 mg/kg body weight) in spontaneously hypertensive rats (SHR) fed a diet containing 60 % fructose, a widely used model of the metabolic syndrome. Surprisingly, we observed acute toxic effects of telmisartan. Rats lost body weight rapidly and died within 2 to 3 weeks due to bleeding into the upper gastrointestinal tract. SHR fed a high fructose diet and treated with telmisartan exhibited rapid decrease in blood pressure when compared to the SHR fed a high fructose diet and treated with valsartan. Concentrations of both unconjugated telmisartan and telmisartan glucuronide in the liver of SHR rats fed a high fructose diet were approximately 4 fold higher when compared to Brown Norway (BN) rats fed the same diet. Plasma concentrations of unconjugated telmisartan in the SHR were about 5 fold higher when compared to BN rats while plasma levels of telmisartan glucuronide were similar between the strains. Testing of other rat strains, diets, and the ARB valsartan showed that toxic effects of telmisartan in combination with high fructose diet are specific for the SHR. These results are consistent with the possibility that in some circumstances, SHR are predisposed to telmisartan toxicity possibly because of a genetically determined disturbance in telmisartan metabolism.
- MeSH
- antihypertenziva toxicita MeSH
- dietní cukry aplikace a dávkování toxicita MeSH
- fruktosa aplikace a dávkování toxicita MeSH
- gastrointestinální trakt účinky léků patologie MeSH
- hypertenze genetika patologie MeSH
- krysa rodu Rattus MeSH
- potkani inbrední SHR MeSH
- potkani Wistar MeSH
- telmisartan toxicita MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antihypertenziva MeSH
- dietní cukry MeSH
- fruktosa MeSH
- telmisartan MeSH
