Iontropes

Benzodiazepines are medications that are widely used for a number of different therapeutic indications and in a wide range of patients in terms of age and health status. Presented here is a simple 2 by 2 way of classifying all of the most commonly used benzodiazepines. This conceptualization is based on the most clinically relevant ways of differentiating these drugs: (a) their affinity for their common and predominant mechanism of action, the benzodiazepine-binding site of the γ-aminobutyric acid (GABA)-A iontropic receptor (ie, the chloride ion channel); and (b) their pharmacokinetics (ie, their half-lives and metabolism)...

Oxalic acid, an effective metal-chelating ligand, is abundant in natural resources. In this study, a chitosan-oxalate complex biosorbent (COCB) was prepared by an iontropic cross-linking method. The COCB beads were characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The XRD analysis shows that Cu(II) ions can form complexes with chitosan and oxalate. Adsorption of Cu(II) ions onto COCB beads was pH-dependent. The isothermal adsorption data fitted well to Langmuir equation with the maximum adsorption capacities of 227...

Kynurenic acid (KYNA) was found to be an antagonist of iontropic glutamate receptors and alpha7 nicotinic acetylcholine receptors. Furthermore, it was documented that KYNA is an agonist of G-protein coupled GPR35 receptors which are mainly present in the gastrointestinal tract. It was also found that KYNA is present in the gastrointestinal tract and that its concentration gradually increases along it. The origin of KYNA in the gastrointestinal tract is not known. Both might be synthesized from tryptophan in it or absorbed from food and other dietary products...

In the study, a novel chitosan (CS) derivative conjugated with multiple galactose residues in an antennary fashion (Gal-m-CS) was synthesized. A galactosylated CS (Gal-CS) was also prepared by directly coupling lactobionic acid on CS. Using an iontropic gelation method, CS and the synthesized Gal-CS and Gal-m-CS were used to prepare nanoparticles (CS, Gal-CS, and Gal-m-CS NPs) for targeting hepatoma cells. TEM examinations showed that the morphology of all three types of NPs was spherical in shape. No aggregation or precipitation of NPs in an aqueous environment was observed during storage for all studied groups, as a result of the electrostatic repulsion between the positively charged NPs...

Glutamate receptors have multiple roles in the central nervous system. Recent evidence suggests that the iontropic glutamate receptors are critical during brain development, particularly for corticogenesis, neuronal migration, and synaptogenesis. In this study, we examined subunit mRNA expression and binding sites of the NMDA, AMPA, and kainate receptors from gestational weeks 8-20 in human fetal brain. Expression of glutamate receptors was high during several periods in these brains. Different levels of expression of each NMDA, AMPA, and kainate receptor subunit transcripts were present during development, with a greater abundance of NR1, NR2B, NR2D, GluR7, and KA1 mRNA at most gestational ages...

The effects of oleamide, an amidated lipid isolated from the cerebrospinal fluid of sleep-deprived cats, on serotonin receptor-mediated responses were investigated in cultured mammalian cells. In rat P11 cells, which endogenously express the 5-hydroxytryptamine2A (5HT2A) receptor, oleamide significantly potentiated 5HT-induced phosphoinositide hydrolysis. In HeLa cells expressing the 5HT7 receptor subtype, oleamide caused a concentration-dependent increase in cAMP accumulation but with lower efficacy than that observed by 5HT...

1. The Drosophila melanogaster gamma-aminobutyric acid (GABA) receptor subunits, RDLac and DRC 17-1-2, form functional homo-oligomeric receptors when heterologously expressed in Xenopus laevis oocytes. The subunits differ in only 17 amino acids, principally in regions of the N-terminal domain which determine agonist pharmacology in vertebrate ionotropic neurotransmitter receptors. A range of conformationally restricted GABA analogues were tested on the two homo-oligomers and their agonists pharmacology compared with that of insect and vertebrate iontropic GABA receptors...

Release of [3H]arachidonic acid mediated by excitatory amino acid (EAA) receptors was investigated from prelabelled primary cultures of hippocampal neurons and astroglial cells. Treatment with N-methyl-D-aspartate (NMDA), quisqualate (QA) and kainate resulted in age- and dose-dependent stimulation of [3H]arachidonic acid release. During development, the maximum response for NMDA was observed relatively earlier (at 7 days) than those for QA and kainate (at 14 days) in the hippocampal neuronal cultures. The half maximal effects were obtained at about 15 microM NMDA at all ages studied and about 0...

The actions of procainamide and its major metabolite N-acetylprocainamide were tested and compared on isolated rat atria. While procainamide exerted a negative chronotropic and iontropic effect, N-acetylprocainamide had the opposite effect. It is suggested that a N-acetylprocainamide-induced increase in myocardial work can counteract the negative inotropic action of procainamide and thus to some extent explain the variable results with the latter compound on myocardial performance reported from in vivo experiments...

1 The influence of ouabain (0.4 muM) on contractile force and cellular Na and K concentrations was investigated in isolated left atria of the guinea-pig at rest and at different beat frequencies. Simultaneously the binding of ouabain to the tissue was determined.2 Strict dependence of rates of onset of positive iontropic action and of binding of ouabain on beat frequency are limited to conditions where no alterations of cellular Na and K concentrations occur. A correlation was observed between sodium flux per unit time and the development of positive inotropism and binding to the receptors of ouabain...

The effects of acetylation of sympathomimetic amines, tyramine, amphetamine, ephedrine, phenylephrine, orciprenaline, and salbutamol, and their O- and N-acetyl derivatives and the effects of reserpine or physostigmine pretreatment on the isolated auricles and tracheal chain of guinea-pigs have been studied. All the parent drugs relaxed the tracheal chain and had a positive inotropic and chronotropic effect on the isolated auricles; only amphetamine, on the contrary, contracted the tracheal chain. O-acetylation of these sympathomimetic amines generally decreased less chronotropic than iontropic action on the isolated auricles...

The new sulphonylurea CS 476 was tested for positive iontropic effect on the isolated cat papillary muscle. Unlike tolbutamide CS 476 had no positive inotropic effect. CS 476 had no adverse effect on blood pressure in dogs, cats and rats nor on the electrocardiogram of dogs in doses up to ten times the therapeutic dose. Unlike chlorpromide CS 476 did not potentiate the effect of exogenous antidiuretic hormone in hydrated dogs. In therapeutic concentrations the drug had no effect on smooth muscle preparations...