We have evaluated the ability of various opioid agonists, including methadone, l-α-acetylmethadol (LAAM), fentanyl, meperidine, codeine, morphine, and buprenorphine, to block cardiac human <i>ether-a-go-go</i>-related gene (HERG) K⁺current (I_HERG) in cells stably transfected with HERG potassium channel gene. Our results show that LAAM, buprenorphine were effective inhibitors I_HERG, IC₅₀ values 1 10 μM range. The other drugs tested far less potent...

KCNQ1 encodes KCNQ1, which belongs to a family of voltage-dependent K + ion channel proteins. associates with regulatory subunit, KCNE1, produce the cardiac repolarizing current, I Ks . Loss-of-function mutations in human gene have been linked Jervell and Lange–Nielsen Syndrome (JLNS), disorder characterized by profound bilateral deafness phenotype. To generate mouse model for JLNS, we created line transgenic mice that targeted disruption Kcnq1 gene. Behavioral analysis revealed −/− are deaf...

Numerous medications prolong the rate-corrected QT (QTc) interval and induce arrhythmias by blocking ionic current through cardiac potassium channels composed of subunits expressed human ether-a-go-go-related gene (HERG). Recent reports suggest that high doses methadone cause torsades de pointes. To date, no controlled study has described an association between QTc prolongation. The only commercial formulation parenteral available in United States contains preservative chlorobutanol....

Women are known to have a longer electrocardiographic Q-T than men, which may contribute their being at greater risk of developing drug-induced polymorphic ventricular arrhythmias. However, little is about the underlying mechanisms. In present study, we evaluated potential gender differences in interval isolated perfused rabbit hearts using Langendorff technique and density outward potassium currents single myocytes whole-cell patch-clamp technique. We found that female demonstrated...

The purpose of the present study was to comparatively evaluate human <i>HERG</i> currents and QT intervals following challenge with suspected torsadogenic nontorsadogenic drugs. Various concentrations 14 different drugs were initially evaluated in terms their relative potency block I_HERG stably transfected embryonic kidney cells. Four general categories identified: high-potency blockers (IC₅₀ &lt; 0.1 μM) included lidoflazine, terfenadine, haloperidol; moderate-potency...

The immediate early gene transcription factor Egr-1 increases luciferase reporter activity 3-4-fold when a rat phenylethanolamine N-methyltransferase (PNMT) promoter-luciferase construct and an expression are cotransfected into transformed PC12 cells (RS1). also stimulates endogenous PNMT mRNA in the RS1 cells. Furthermore, transfected treated with dexamethasone, both rise additional 2-fold although dexamethasone does not independently activate from promoter. While sites (-45 -165 base...

The rat phenylethanolamine N-methyltransferase (PNMT) gene contains overlapping consensus elements for the Sp1 and Egr-1 transcription factors located at −45 bp −165 in PNMT promoter. In present study, we show that can specifically bind to these elements, this binding appears be mutually exclusive, site occupancy is dependent upon concentration of each factor its affinity site. binds with relatively high (IC50 = 14 nM) low 1360 nM), whereas both sites intermediate affinities 210 140 nM,...

Tamoxifen is an antiestrogen drug commonly used to treat breast cancer and has been shown cause prolongation of the electrocardiographic QT interval in humans. Because could influence cardiac arrhythmias, we sought determine electrophysiologic mechanism(s) underlying tamoxifen action. The whole-cell patch-clamp technique was study effect on delayed rectifier (IKr), inward (IK1), transient outward current (Ito), L-type calcium (ICa) rabbit ventricular myocytes. By switching current-clamp...

Abstract —Epinephrine is a potent neurotransmitter and hormone that can influence cardiac performance beginning shortly after the first myocardial contractions occur in developing vertebrate embryos. In present study, we provide evidence heart itself may produce epinephrine during embryonic development. Using antibodies selectively recognize catecholamine biosynthetic enzymes, tyrosine hydroxylase, dopamine β-hydroxylase, phenylethanolamine N-methyltransferase, used coimmunofluorescent...

Abstract To evaluate the developmental distribution of adrenergic cells in vivo, we inserted Cre‐recombinase gene into locus encoding for epinephrine biosynthetic enzyme phenylethanolamine n‐methyltransferase (Pnmt) and crossed these Pnmt‐Cre mice with ROSA26 reporter (R26R) to activate LacZ (encoding β‐galactosidase) expression that were selectively derived from lineage. Our data show following: (1) Insertion Pnmt created a functional knockout concomitant loss homozygous Cre/Cre mice; (2)...

Recent clinical observations indicate that female gender is associated with a higher risk of developing torsades de pointes (TdP) cardiac arrhythmia. In this study, we used the Langendorff technique in isolated perfused rabbit hearts and whole-cell patch-clamp ventricular myocytes to examine difference TdP incidence gain insight into underlying mechanisms. Isolated were by using technique. was induced abrupt changes cycle length (deltaCL) presence Tyrode's solution containing 1 mM...

Transfection of PC12-variant RS1 cells with an Egr-1 expression construct has previously been shown to stimulate phenylethanolamine N-methyltransferase (PNMT) promoter activity, thus suggesting a putative role as factor regulating PNMT gene expression. To elucidate the physiological implication this finding, effects phorbol 12-myristate 13-acetate (PMA) on activity and were examined. PMA stimulated luciferase in transfected rat promoter-luciferase reporter construct, also elevated both mRNA...

Tegaserod (HTF 919) is a new drug being developed for gastrointestinal motility disorders. Because other prokinetic agents, such as cisapride and erythromycin, cause slowing of cardiac repolarization have been implicated in the development potentially fatal ventricular arrhythmia, torsades de pointes, study was initiated to determine whether tegaserod its main human metabolite adversely influence repolarization. By using isolated Langendorff-perfused rabbit hearts, we show that QT intervals...

The genome of herpes simplex virus type 1 contains a large number recognition sites for eucaryotic DNA II topoisomerase. Topoisomerase were identified by means the consensus sequence described previously (J.R. Spitzner and M.T. Muller, Nucleic Acids Res. 16:5553-5556, 1988) then confirmed sequencing cleavages introduced purified topoisomerase II. In vivo, host also double-stranded breaks in viral at predicted sequence. Host acted on all immediate-early genes as well from other temporal...

As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP ATP in mitochondria becomes vital. Relatively little, however, is known about signaling mechanisms regulating transition anaerobic aerobic metabolism that occurs during period. The main objective this study was test hypothesis adrenergic hormones provide critical stimulation embryonic/fetal development. We examined concentrations mouse embryos...

We examined the effects of "conventional" antihistamines on cardiac repolarization by using isolated perfused feline heart model. Representative drugs from major classes were tested. Each evaluated in this study elicited a dose-dependent slowing repolarization, as indicated QT prolongations observed electrocardiogram (ECG) tracings recorded during these experiments. The concentrations tested ranged 1 to 30 μM. Of analyzed, clemastine and hydroxyzine appeared be most potent (relative EC50...

Endogenous host topoisomerase II acts upon herpes simplex virus type 1 (HSV-1) DNA in infected cells (S.N. Ebert, S.S. Shtrom, and M.T. Muller, J. Virol. 56:4059-4066, 1990), cleavage is directed exclusively at progeny viral while parental resistant. To evaluate the possibility that HSV-1 induces activity which could account for preferential of DNA, we assessed on cellular substrates before after initiation replication. We show a gene mock-infected was similar to observed HSV-1-infected...

Abstract Objective Follistatin (FS) is the specific binding protein of activin and expression both factors regulated by inflammatory agents. Therefore, FS concentrations were determined in cerebrospinal fluid (CSF) patients with bacterial viral meningitis or multiple sclerosis (MS), as well CSF without meningial inflammation autoimmune diseases. Furthermore, a mouse pneumococcal model was used to localise cellular sources brains normal meningitic mice. Methods ELISA; mice localised situ...

Antiretroviral therapy (ART) has significantly reduced the rate of mortality in HIV infected population, but people living with (PLWH) show higher rates cardiovascular disease (CVD). However, effect antiretroviral (ARV) drug treatment on cardiac cells is not clear. In this study, we explored ARV drugs cardiomyocyte epigenetic remodeling. Primary cardiomyocytes were treated a combination four (ritonavir, abacavir, atazanavir, and lamivudine), changes examined. Our data suggest that reduces...

Abstract Background Environmental factors may influence the development of tetralogy Fallot (TOF), and DNA methylation patterns reveal specific chemical signatures perturbations during cardiac development. We investigated whether blood buccal cells could be viable surrogates for myocardium. Methods measured epigenome‐wide at 866,895 5’‐cytosine‐phosphate‐guanine‐3’ (CpG) sites in (n=3), right ventricular myocardium (n=4) collected from infants with TOF compared percent differentially...

Cardiac calsequestrin (Casq2) associates with the ryanodine receptor 2 channel in junctional sarcoplasmic reticulum to regulate Ca2+ release into cytoplasm. Patients carrying mutations CASQ2 display low resting heart rates under basal conditions and stress-induced polymorphic ventricular tachycardia (CPVT). In this study, we generate characterize novel conditional deletion rescue mouse models test influence of developmental programs on rate CPVT phenotypes. We also compare requirements for...