The effective concentration of a drug in the blood, i.e. the concentration of a free drug in the blood, is influenced by the strength of drug binding onto plasma proteins. Besides its efficacy, these interactions subsequently influence the liberation, absorption, distribution, metabolism, excretion, and toxicological properties of the drug. It is important to not only determine the binding strength and stoichiometry, but also the binding site of a drug on the plasma protein molecule, because the co-administration of drugs with the same binding site can affect the above-mentioned concentration and as a result the pharmacological behavior of the drugs and lead to side effects caused by the change in free drug concentration, its toxicity. In this study, the binding characteristics of six drugs with human serum albumin, the most abundant protein in human plasma, were determined by capillary electrophoresis-frontal analysis, and the obtained values of binding parameters were compared with the literature data. The effect of several drugs and site markers on the binding of l-tryptophan and lidocaine to human serum albumin was investigated in subsequent displacement studies which thus demonstrated the usability of capillary electrophoresis as an automated high-throughput screening method for drug-protein binding studies.

• MeSH
• chlorpropamid analýza   farmakologie   MeSH
• diklofenak analýza   farmakologie   MeSH
• elektroforéza kapilární MeSH
• fenylbutazon analýza   farmakologie   MeSH
• flurbiprofen analýza   farmakologie   MeSH
• ibuprofen analýza   farmakologie   MeSH
• lidé MeSH
• lidokain antagonisté a inhibitory   chemie   MeSH
• lidský sérový albumin chemie   MeSH
• tolbutamid analýza   farmakologie   MeSH
• tryptofan antagonisté a inhibitory   chemie   MeSH
• vazebná místa účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Despite the urgent need for assays to visualize insulin secretion there is to date no reliable method available for measuring insulin release from single cells. To address this need, we developed a genetically encoded reporter termed RINS1 based on proinsulin superfolder GFP (sfGFP) and mCherry fusions for monitoring insulin secretion. RINS1 expression in MIN6 β cells resulted in proper processing yielding single-labeled insulin species. Unexpectedly, glucose or drug stimulation of insulin secretion in β cells led to the preferential release of the insulin-sfGFP construct, while the mCherry-fused C-peptide remained trapped in exocytic granules. This physical separation was used to monitor glucose-stimulated insulin secretion ratiometrically by total internal reflection fluorescence microscopy in single MIN6 and primary mouse β cells. Further, RINS1 enabled parallel monitoring of pulsatile insulin release in tolbutamide-treated β cells, demonstrating the potential of RINS1 for investigations of antidiabetic drug candidates at the single-cell level.

• MeSH
• beta-buňky cytologie   účinky léků   metabolismus   sekrece   MeSH
• biosenzitivní techniky MeSH
• buněčné linie MeSH
• fluorescenční mikroskopie MeSH
• glukosa farmakologie   MeSH
• hypoglykemika farmakologie   MeSH
• inzulin metabolismus   sekrece   MeSH
• luminescentní proteiny genetika   metabolismus   MeSH
• myši MeSH
• rekombinantní fúzní proteiny metabolismus   sekrece   MeSH
• reportérové geny MeSH
• tolbutamid farmakologie   MeSH
• vápník metabolismus   MeSH
• zelené fluorescenční proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

In the present study, we investigated hepatic mRNA expression and activities of CYP3A and 2C in entire, surgically castrated and pigs vaccinated with Improvac. Additionally, we examined the mRNA expression of the two nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR), known to regulate CYP3A and 2C mRNA expression, respectively. Activities of CYP3A and 2C were estimated as a rate of 7-benzyloxy-4-trifluoromethylcoumarin and 7-benzyloxyquinoline metabolism (CYP3A) and tolbutamide metabolism (CYP2C). We found no effect of Improvac treatment or surgical castration on either CYP3A or 2C activities. Similarly, the mRNA expressions of CYP3A29, 2C33 and PXR were not changed. CAR mRNA expression differed only between entire and surgically castrated male pigs (p=0.005), being greater in surgically castrated pigs. Our results indicated that neither CYP3A nor 2C are affected by Improvac.

• MeSH
• antikoncepční vakcíny aplikace a dávkování   škodlivé účinky   MeSH
• chinoliny metabolismus   MeSH
• cytochrom P-450 CYP3A biosyntéza   MeSH
• exprese genu účinky léků   MeSH
• játra enzymologie   MeSH
• kastrace škodlivé účinky   MeSH
• kumariny metabolismus   MeSH
• prasata MeSH
• receptory cytoplazmatické a nukleární biosyntéza   MeSH
• steroidní receptory biosyntéza   MeSH
• systém (enzymů) cytochromů P-450 biosyntéza   MeSH
• tolbutamid metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Aims. We previously reported the effect of St John's wort (Hypericum perforatum) standardised extract LI 160 on the activities of cytochrome P450 2C6, 2D2 and 3As (Dostalek et al., Life Sciences 2005;78(3):239-44). In this study, we aimed to assess the effect of St John's wort on the activity of cytochrome P450 1A2. Methods. The isolated perfused rat liver model was used in our experiments with phenacetin as a marker substrate for cytochrome P450 1A2. Male Wistar rats were treated with St John's wort extract (100 mg/kg, once daily for 10 days); comparative inhibitor (alpha-naphthoflavone, 100 mg/kg) or comparative inducer (omeprazole, 30 mg/kg). Results. The rate of formation of acetaminophen was significantly inhibited by the use of St John's wort (P<0.001). In addition, St John‘s wort extract inhibited cytochrome P450 1A2 activity significantly more than the control inhibitor (P<0.001). Conclusions. St John's wort significantly inhibited cytochrome P450 1A2 enzyme activity. It remains to be determined whether the co-administration of St John‘s wort extract and other medications or substrates for cytochrome P450 1A2 could result in significant drug interactions.

• MeSH
• antidepresiva farmakologie   MeSH
• dextromethorfan farmakokinetika   MeSH
• fenacetin farmakokinetika   metabolismus   MeSH
• financování organizované MeSH
• injekce intraperitoneální MeSH
• interakce bylin a léků MeSH
• játra enzymologie   účinky léků   enzymologie   metabolismus   účinky léků   MeSH
• krysa rodu rattus MeSH
• midazolam farmakokinetika   MeSH
• paracetamol farmakokinetika   metabolismus   MeSH
• perfuze MeSH
• plocha pod křivkou MeSH
• potkani Wistar MeSH
• rostlinné extrakty farmakologie   MeSH
• systém (enzymů) cytochromů P-450 antagonisté a inhibitory   biosyntéza   metabolismus   MeSH
• tolbutamid farmakokinetika   MeSH
• třezalka MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• techniky in vitro MeSH

A new, simple, rapid, sensitive, and repeatable reversed-phase HPLC method was developed and validated for the simultaneous determination of tolbutamide, phenacetin and their metabolites in rat liver perfusate. Chlorpropamide was used as an internal standard to ensure the precision and accuracy of this method. Analytes were extracted into diethyl ether using a two-step liquid-liquid extraction. A C18 analytical column and a mobile phase composed of acetonitrile and potassium phosphate buffer were used for the chromatographic separation with UV detection. Limits of detection varied between 20 and 46ng/mL for phenacetin, tolbutamide and their metabolites. The overall extraction recovery for the analytes varied from 65.4% in paracetamol to 88.0% in tolbutamide for concentrations within the expected range of concentrations from previous experimental samples. In terms of precision, the intra- and inter-day variation at three different concentrations in all analytes never exceeded 7.6 and 11.4%, respectively. This method is applicable for the modeling and description of possible pharmacological interactions on rat cytochromes P450 1A2 and 2C6/11 or can be used for in vitro evaluation of both cytochromes 1A2 and 2C.

• MeSH
• aromatické hydroxylasy metabolismus   MeSH
• biologické markery metabolismus   MeSH
• biologické modely MeSH
• cytochrom P-450 CYP1A2 metabolismus   MeSH
• fenacetin metabolismus   MeSH
• játra enzymologie   MeSH
• krysa rodu rattus MeSH
• lékové interakce fyziologie   MeSH
• perfuze metody   MeSH
• potkani Wistar MeSH
• steroid-16-alfa-hydroxylasa metabolismus   MeSH
• steroid-21-hydroxylasa metabolismus   MeSH
• tolbutamid metabolismus   MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

OBJECTIVES: A "cocktail" of several substrates is frequently used to assess metabolic activity of multiple cytochrome P450 enzymes in one session. Some interactions among substrates can appear and may influence the rate of biotransformation of other ones. Our current work was aimed on the influence of tolbutamide on cytochrome P450-mediated metabolism of phenacetin and vice versa. DESIGN: In the presented work, the biotransformation rates of phenacetin and tolbutamide (markers of rat CYP1A2 and CYP2C6/11 metabolic activities, respectively) administered either separately or both simultaneously were compared. The model of isolated perfused rat liver was used. RESULTS: Phenacetin had no significant effect on tolbutamide hydroxylation. Tolbutamide addition to the perfusion medium significantly increased the rate of O-deethylation of phenacetin. CONCLUSION: Some differences in the rate of P450-mediated metabolism can be observed when comparing assessment using combination of two model substrates with the common way (single marker administration). Due to these differences, results obtained by the mentioned methodologies might not be fully comparable.

• MeSH
• biotransformace MeSH
• časové faktory MeSH
• fenacetin metabolismus   farmakologie   MeSH
• játra účinky léků   metabolismus   MeSH
• krysa rodu rattus MeSH
• potkani Wistar MeSH
• systém (enzymů) cytochromů P-450 chemie   metabolismus   MeSH
• tolbutamid metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The present study investigated the effect of the aqueous extract of Helicteres isora L (Sterculiaceae) bark on oxidative stress in the heart of rats during diabetes. The aqueous extract of Helicteres isora bark (100 mg, 200 mg/kg body weight (b.w.)) was screened for its antioxidant effect in streptozotocin (STZ) induced diabetic rats. An appreciable decrease in peroxidation products, thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), and hydroperoxides (HP) was observed in the heart tissues of Helicteres isora (HI) treated diabetic rats. The decreased activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-tranferase (GST) and glutathione (GSH) in diabetic rats were brought back to near normal range upon HI treatment. Tolbutamide was used as the standard reference drug. These results suggest that HI possesses promising antioxidative activity in STZ diabetic rats.

• MeSH
• experimentální diabetes mellitus komplikace   metabolismus   MeSH
• katalasa farmakokinetika   metabolismus   MeSH
• peroxidace lipidů genetika   účinky záření   MeSH
• potkani Wistar MeSH
• reaktivní formy kyslíku metabolismus   škodlivé účinky   MeSH
• rostlinné extrakty farmakokinetika   metabolismus   MeSH
• slézovité metabolismus   účinky léků   MeSH
• streptozocin metabolismus   škodlivé účinky   MeSH
• superoxiddismutasa farmakokinetika   metabolismus   MeSH
• tolbutamid farmakokinetika   metabolismus   MeSH

Perorální antidiabetika (PAD) jsou preparáty určené výhradně k léčbě diabetes mellitus 2. typu (T2D). V rámci léčby T2D se snažíme ovlivnit jak inzulinorezistenci, tak i poruchu inzulinové sekrece. Lze volit preparáty, které ovlivňují především lačnou glykemii (metformin, thiazoli­dindiony) a preparáty ovlivňující především postprandiální glykemii (akarbóza, inzulinová sekretagoga, inkretin-mimetika), cílem je optimální metabolická kontrola. Inkretin-mimetika, zasahující na více hladinách regulace glukózy, jsou kvalitativně novou složkou v antidiabetické medikaci. Pro vhodného pacienta je možné zvolit i kombinaci různých typů perorálních antidiabetik, popř. i kombinaci PAD a inzulinu.

Oral antidiabetic agents (OAD) are preparations used in Type 2 Diabetes mellitus treatment. There is important to manage both metabolic disorders in diabetic patients?– impaired insulin sensitivity and dysfunction in insulin secretion as well. Basic tools in optimal metabolic control are preparations that influence mainly fasting glycemia (metformin, thiazolidindions) and mainly postprandial glycemia (acarbose, insulin secretagogues, incretin mimetics). Incretin mimetics work in more levels of glucose metabolism regulations and form a new quality in antidiabetic treatment. There is possible to combine various species of oral antidiabetic agents or combine OAD with insulin therapy.

• MeSH
• alfa-glukosidasy antagonisté a inhibitory   terapeutické užití   MeSH
• aplikace orální MeSH
• biguanidy farmakologie   terapeutické užití   MeSH
• diabetes mellitus 2. typu farmakoterapie   MeSH
• fixní kombinace léků MeSH
• hypoglykemika klasifikace   terapeutické užití   MeSH
• inhibitory dipeptidylpeptidasy 4 terapeutické užití   MeSH
• inkretiny aplikace a dávkování   toxicita   MeSH
• inzulinová rezistence MeSH
• lidé MeSH
• thiazolidindiony farmakologie   terapeutické užití   MeSH
• tolbutamid terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

• MeSH
• chlorpropamid farmakologie   terapeutické užití   MeSH
• diabetes mellitus 2. typu * farmakoterapie   MeSH
• gliklazid farmakologie   terapeutické užití   MeSH
• glipizid farmakologie   terapeutické užití   MeSH
• hypoglykemika * farmakologie   terapeutické užití   MeSH
• kardiovaskulární nemoci MeSH
• klinická studie jako téma MeSH
• lékové interakce MeSH
• lidé MeSH
• metabolický syndrom farmakoterapie   MeSH
• nežádoucí účinky léčiv MeSH
• sulfonylmočovinové sloučeniny * farmakokinetika   farmakologie   kontraindikace   terapeutické užití   MeSH
• tolbutamid farmakologie   terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH

The present investigation shows the antihyperglycaemic activity of aqueous extract of bark of Helicteres isora L. (100, 200mg/kg b.w/p.o) in streptozotocin (STZ) induced diabetic rats. Blood glucose levels, body weight, food and liquid intake were measured on every 5th day over a period of 14 days. A single injection of STZ at a dose of 60mg/kg b.w/i.p elevated the glucose levels >240mg/dl after 5 days. Administration of H.isora at a dose of 100, 200mg/kg/p.o resulted in a significant (p<0.05) reduction in blood glucose levels. Body weights were significantly (p<0.05) reduced in STZ-induced diabetic rats when compared to normal rats while the extract significantly (p<0.05) prevented a decrease in body weight in the H.isora treated animals. The study also evaluated the antioxidant potential of H.isora in STZ-induced diabetic rats. Decreased levels of thiobarbituric acid reactive substances (TBARS), increased levels of reduced glutathione (GSH) and the activities of superoxide dismutase (SOD) and catalase (CAT) resulted in the reduction of free radical formation in various tissues such as liver, kidney, and brain of the diabetic rats. Tolbutamide was used as a standard reference drug. The results clearly indicate that the aqueous extract of bark of Helicteres isora exhibits significant antihyperglycaemic and in vivo antioxidant activity in STZ-induced diabetic rats and the results were found to be dose dependent.

• MeSH
• antioxidancia terapeutické užití   MeSH
• experimentální diabetes mellitus komplikace   metabolismus   MeSH
• hypoglykemika terapeutické užití   MeSH
• katalasa farmakokinetika   metabolismus   MeSH
• kůra rostlin MeSH
• peroxidace lipidů genetika   účinky záření   MeSH
• potkani Wistar metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   škodlivé účinky   MeSH
• rostlinné extrakty farmakokinetika   metabolismus   terapeutické užití   MeSH
• slézovité chemie   metabolismus   účinky léků   MeSH
• streptozocin metabolismus   škodlivé účinky   MeSH
• superoxiddismutasa farmakokinetika   metabolismus   MeSH
• tolbutamid farmakokinetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH