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At least 19 recordsLinked to original sources
PubMed1971

Synthesis and oxidation of aminoalkyl-onium compounds by pig kidney diamine oxidase.

1. The preparation of a series of compounds derived from diamines by replacing one amino group by a dimethylsulphonium, isothiuronium, trimethylammonium, NN'-dimethylimidazolium or N-methylpyridinium species is described. 2. The behaviour of these compounds as substrates of pig kidney diamine oxidase is reported. All but the trimethylammonium compounds proved to be substrates. 3. Many of these compounds showed potent inhibition at high substrate concentration and this was studied. 4. On the basis of these and other observations a scheme for enzyme-substrate interaction is suggested.

Alkanes↗
PubMed1963

The action of substances which block sympathetic postganglionic nervous transmission.

The substances which block sympathetic postganglionic transmission, xylocholine, bretylium and guanethidine, also block neuromuscular and sympathetic ganglionic transmission. To see if these last properties were related to the sympathetic blocking property, phenyltrimethylammonium, which blocks the neuromuscular junction (Riker, 1953), was used. It blocked the inhibition of the rabbit ileum produced by stimulating the periarterial nerves in the mesentery, though with higher concentrations the effect of stimulation was initially increased. The action was not modified by the presence of hyoscine. The blocking action was exerted on the response to stimulation of the highest frequency first, and on the response to stimulation of the lowest frequency last. This relation of block to stimulus frequency is similar to that at the neuromuscular junction when tubocurarine is used. Nine compounds have now been shown to block responses to sympathetic postganglionic stimulation, and seven of these are onium compounds. They are, however, mon-onium compounds, and not bis-onium compounds like hexamethonium and decamethonium, so that they can probably enter the postganglionic fibre, which bis-onium compounds (having a charged group at each end of the molecule) may not be able to do. Since these mon-onium compounds have some blocking action at neuromuscular junctions and at sympathetic ganglia, their block of postganglionic transmission may be essentially similar to that by hexamethonium at ganglia and to that by decamethonium at neuromuscular junctions. It is known that acetylcholine releases noradrenaline from sympathetic postganglionic terminations, and xylocholine and bretylium block this release in the vessels of the rabbit ear and in the rabbit isolated atria.

Acetylcholine↗
PubMed1975

Influence of extracellular calcium and a water-soluble carboxyl group reagent on cholinergic drug-receptor interactions in skeletal muscle.

Contractions of frog rectus abdominus muscles induced by suxamethonium or decamethonium, and to a lesser extent by carbamylcholine, were decreased as the extracellular calcium concentration was increased. The inhibition of all three agonist responses by 1.1 mM calcium was competitive. The contractions induced by bis-onium compounds, but not carbamylcholine, were further antagonized at higher calcium concentrations (4.4 mM) in a noncompetitive manner. This latter effect of calcium may be due to antagonism of bis-onium compounds at a peripheral anionic site. Carboxyl group carbodiimide reagents inhibited muscle contractions, and this inhibition was slowly reversible. The extent of the inhibition was increased, and its recovery delayed, by prior exposure of the muscle to an agonist. The results support suggestions that receptor activation initially involves displacement of membrane calcium. The study provides further evidence that interaction of agonists iwth nicotinic receptors results in structural changes, possibly related to increased ion flow.

Animals↗
PubMed1972

Inhibition of pig kidney diamine oxidase by substrate analogues.

1. The oxidation of p-dimethylaminomethylbenzylamine was followed spectrophotometrically by measuring the change in E(250) caused by the p-dimethylaminomethylbenzaldehyde produced. 2. This reaction was inhibited by substrate analogues such as isothiouronium, guanidino, dimethylsulphonium and trimethylammonium compounds. 3. The inhibition by both mono- and bis-onium compounds has been studied and a comprehensive theory is developed to explain both the type and degree of inhibition produced.

Amine Oxidase (Copper-Containing)↗
PubMed1974

The inhibition of human placental diamine oxidase by substrate analogues.

1. The oxidation of p-dimethylaminomethylbenzylamine by purified placental diamine oxidase was followed by measuring the change in E(250) caused by the production of p-dimethylaminomethylbenzaldehyde. 2. The inhibition of this reaction by substrate analogues such as isothiouronium, guanidinium, dimethylsulphonium and trimethylammonium compounds was extensively studied. 3. The type and degree of inhibition by mono- and bis-onium compounds is described, and a theory is developed to explain the type of inhibition produced.

Amine Oxidase (Copper-Containing)↗
PubMed1976

Interaction of hexafluorenium with human plasma cholinesterase in comparison with hexamethonium.

1. The influence of the 2 alkane-bis-onium compounds hexafluorenium (HF1) and hexamethonium (C6) on human plasma cholinesterase (ChE) was studied with respect to the type of inhibition. 2. HF1 and C6 are reversible inhibitors of ChE. The inhibitory potency of HF1 (pI50 = 6.96; Ki = 2.4 x 10(-9)) is about 40 000-fold higher than that of C6 (pI50 = 2.4; Ki = 6.7 x 10(-2)). 3. The kinetic analysis displayed a competitive (C6) and a non-competitive (hf1) mechanism of action. 4. The inhibition of ChE by C6 is induced by a binding of C6 to the anionic site of the active center thus impairing the primary formation of the enzyme-substrate complex. HF1, however, is most probably bound to anionic side receptors in the vicinity of the active center; by that a conformational change of the enzyme protein is induced impairing the acylation step of the esteratic site.

Binding Sites↗
PubMed2002

Aged garlic extract enhances production of nitric oxide.

Nitric oxide (NO) controls several physiological functions of the cardiovascular system. Three kinds of NO synthases (NOSs), neuronal constitutive NOS (ncNOS), inducible NOS (iNOS) and endothelial constitutive NOS (ecNOS), were responsible for NO biosynthesis. This study investigated the effect of aged garlic extract (AGE) on NO production by measuring the NO metabolites nitrite and nitrate in the plasma of mice. AGE (2.86 g/kg, p.o.) temporarily increased NO production by 30-40% from 15 to 60 min after administration. The time course of the fluctuation in NO levels in the AGE-treated group was clearly different to that in a group of mice treated with lipopolysaccharides, a typical iNOS inducer. Arginine (63 mg/kg, p.o.) at the equivalent dose of AGE did not increase NO production. However diphenyleneiodonium chloride (1 mg/kg, i.p.), a selective cNOS inhibitor, administered prior to AGE, overcame the effect of AGE. These results indicate that AGE increased NO production by activating cNOS, but not iNOS. The arginine contained in AGE was not responsible for the effect. AGE may be a useful tool for the prevention of cardiovascular disease.

Animals↗