ABSTRACT
To investigate the relationship between the pharmacokinetics (PK) and effects and/or side-effects of nifedipine and propranolol, simultaneous examination of their PK and pharmacodynamics (PD), namely blood pressure (BP), heart rate (HR), and QT interval (QT), were assessed in spontaneously hypertensive rats as a disease model. Drugs were infused intravenously for 30 min, then plasma PK and hemodynamic effects were monitored. After general two-compartmental analysis was applied to the plasma data, PD parameters were calculated by fitting the data to PK-PD models. After nifedipine administration, the maximal hypotensive effect appeared about 10 min after starting the infusion, then BP started to elevate although the plasma concentration increased, supposedly because of a negative feedback mechanism generated from the homeostatic mechanism. After propranolol administration, HR decreased by half, and this bradycardic effect was greater than that with nifedipine. Wide variation in QT was observed when the propranolol concentration exceeded 700 ng/mL. This variation may have been caused by arrhythmia. Prolongation of QT with propranolol was greater than that with nifedipine, and bradycardia was slower than the concentration increase and QT prolongation. The characteristically designed PK-PD model incorporating a negative feedback system could be adequately and simultaneously fitted to both observed effect and side-effects.
Subject(s)
Adrenergic beta-Antagonists/pharmacokinetics , Antihypertensive Agents/pharmacokinetics , Blood Pressure/drug effects , Calcium Channel Blockers/pharmacokinetics , Hypertension/drug therapy , Nifedipine/pharmacokinetics , Propranolol/pharmacokinetics , Action Potentials/drug effects , Adrenergic beta-Antagonists/administration & dosage , Adrenergic beta-Antagonists/blood , Adrenergic beta-Antagonists/toxicity , Animals , Antihypertensive Agents/administration & dosage , Antihypertensive Agents/blood , Antihypertensive Agents/toxicity , Calcium Channel Blockers/administration & dosage , Calcium Channel Blockers/blood , Calcium Channel Blockers/toxicity , Disease Models, Animal , Feedback, Physiological , Heart Rate/drug effects , Hypertension/blood , Hypertension/physiopathology , Infusions, Intravenous , Male , Models, Biological , Models, Statistical , Nifedipine/administration & dosage , Nifedipine/blood , Nifedipine/toxicity , Propranolol/administration & dosage , Propranolol/blood , Propranolol/toxicity , Rats, Inbred SHR , Risk AssessmentABSTRACT
We examined the intrinsic cell permeability of a GAGA zinc finger obtained from the Drosophila melanogaster transcription factor and analyzed its mechanism of cellular uptake using confocal microscopy and flow cytometry. HeLa cells were treated with the Cy5-labeld GAGA peptides (containing a fluorescent chromophore) to detect fluorescence signals from the fluorescent labeling peptides by confocal microscopy. The results clearly indicated that GAGA peptides possess intrinsic cell permeability for HeLa cells. Based on the results of the flow cytometry analysis and the theoretical net positive charge of the GAGA peptides, the efficiency of cellular uptake of the GAGA peptides was predicted to depend on the net positive charge of the GAGA peptide as well as the cationic component ratio of Arg residues to Lys residues.
Subject(s)
DNA-Binding Proteins/metabolism , Drosophila Proteins/metabolism , Transcription Factors/metabolism , Zinc Fingers/physiology , Amino Acid Sequence , Animals , Arginine/chemistry , Cell Membrane Permeability , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/genetics , Drosophila Proteins/chemistry , Drosophila Proteins/genetics , Flow Cytometry , HeLa Cells , Humans , Lysine/chemistry , Microscopy, Confocal , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/genetics , Peptide Fragments/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Static Electricity , Transcription Factors/chemistry , Transcription Factors/genetics , Zinc Fingers/geneticsABSTRACT
Interactions of multivalent anionic porphyrins and their iron(III) complexes with cationic peptides, V3(Ba-L) and V3(IIIB), which correspond to those of the V3 loop regions of the gp120 envelope proteins of the HIV-1(Ba-L) and HIV-1(IIIB) strains, respectively, are studied by UV/Vis, circular dichroism, (1)H NMR, and EPR spectroscopy, a microcalorimetric titration method, and anti-HIV assays. Tetrakis(3,5-dicarboxylatophenyl)porphyrin (P1), tetrakis[4-(3,5-dicarboxylatophenylmethoxy)phenyl]porphyrin (P2), and their ferric complexes (Fe(III)P1 and Fe(III)P2) were used as the multivalent anionic porphyrins. P1 and Fe(III)P1 formed stable complexes with both V3 peptides (binding constant K>10(6) M(-1)) through combined electrostatic and van der Waals interactions. Coordination of the His residues in V3(Ba-L) to the iron center of Fe(III)P1 also played an important role in the complex stabilization. As P2 and Fe(III)P2 form self-aggregates in aqueous solution even at low concentrations, detailed analysis of their interactions with the V3 peptides could not be performed. To ascertain whether the results obtained in the model system are applicable to a real biological system, anti-HIV-1(BA-L) and HIV-1(IIIB) activity of the porphyrins is examined by multiple nuclear activation of a galactosidase indicator (MAGI) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. There is little correlation between chemical analysis and actual anti-HIV activity, and the size rather than the number of the anionic groups of the porphyrin is important for anti-HIV activity. All the porphyrins show high selectivity, low cytotoxicity, and high viral activity. Fe(III)P1 and Fe(III)P2 are used for the pharmacokinetic study. Half-lives of these iron porphyrins in serum of male Wistar rats are around 4 to 6 h owing to strong interaction of these porphyrins with serum albumin.