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At least 127 records · Page 7Linked to original sources
PubMed1985

Muscarinic receptor-mediated increase in cytoplasmic free Ca2+ in isolated bovine adrenal medullary cells. Effects of TMB-8 and phorbol ester TPA.

The change in cytoplasmic free calcium, [Ca2+]i in isolated bovine adrenal medullary cells during stimulation by acetylcholine (ACh) in Ca2+-free incubation medium was measured using the fluorescent Ca2+ indicator quin2. ACh (1-100 microM) caused an increase in [Ca2+]i by mobilization of Ca2+ from the intracellular pool. Nicotine (10 microM) did not increase [Ca2+]i in the absence of extracellular Ca2+. Pretreatment of the cells with atropine (10 microM) completely inhibited ACh-induced increase in [Ca2+]i, whereas pretreatment with hexamethonium (100 microM) did not. The intracellular Ca2+ antagonist 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), inhibited ACh-induced increase in [Ca2+]i. The activator of protein kinase C 12-O-tetradecanoylphorbol-13-acetate (TPA), but not its 'inactive' analog 4 alpha-phorbol-12,13-didecanoate (PDD), also inhibited ACh-induced increase in [Ca2+]i. These findings suggest that in bovine adrenal medullary cells, stimulation of muscarinic ACh receptor causes an increase in [Ca2+]i by mobilizing Ca2+ from the intracellular pool and that protein kinase C is involved in 'termination' or 'down regulation' of this response.

Acetylcholine↗
PubMed1984

Effect of trifluoperazine, compound 48/80, TMB-8 and verapamil on ionophore A23187 mediated calcium uptake in ATP depleted human red cells.

The A23187 induced calcium uptake in ATP depleted cells was determined at pH 6.9 in the presence of trifluoperazine (TFP, 0.30 mM), compound 48/80 (0.89 mg/ml), 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8, 2.13 mM) and verapamil (1.81 mM). Apart from verapamil the drugs all increased the maximum rate of ionophore-mediated calcium flux by 50-60 per cent. After the ionophore addition some time elapsed before the calcium flux attained the maximum value, and this time dependence could be interpreted as a slow uptake of A23187 into the membrane: five seconds after the addition of A23187 half of the added ionophore was able to transport calcium through the membrane. The effect of pH on the ionophore-mediated calcium uptake was determined in the absence and presence of TFP. At pH 7.4 the maximum rate of calcium flux in the absence of TFP was two to three times higher than that at pH 6.9 and TFP increased the uptake rate by 98 per cent.

Adenosine Triphosphate↗
PubMed1988

Intracellular Ca2+ antagonist TMB-8 blocks catecholamine secretion evoked by caffeine and acetylcholine from perfused cat adrenal glands in the absence of extracellular Ca2+.

Unlike acetylcholine, caffeine was much more effective in releasing catecholamine in the absence of extracellular Ca2+ than in its presence in perfused cat adrenal glands. The intracellular Ca2+ antagonist, TMB-8 (10(-4) M), inhibited reversibly the catecholamine secretion evoked by caffeine (40 mM) and that induced by acetylcholine (10(-4) M) in the presence of hexamethonium (10(-3) M) during perfusion with Ca2+-free Locke solution containing EGTA (10(-5) M). These results support our view that muscarinic receptor activation causes catecholamine secretion by mobilizing Ca2+ from an intracellular pool just as caffeine does.

Acetylcholine↗
PubMed1986

Ca2+ and phorbol ester activation of protein kinase C at intracellular Ca2+ concentrations and the effect of TMB-8.

A calcium-activated, phospholipid-dependent protein kinase (protein kinase C) was purified to near homogeneity from human polymorphonuclear leukocytes and shown to be identical to bovine protein kinase C. The Ca2+ activation of the enzyme was studied and the Ca2+ concentrations required to activate the enzyme were compared to free cytosolic Ca2+ concentrations in resting and activated polymorphonuclear leukocytes. The free calcium concentrations in the cytosol and in the enzyme assay mixture were determined using the calcium indicator quin 2. The enzyme activity was almost totally dependent upon phosphatidylserine and could be strongly activated by Ca2+ concentrations in the micromolar range, but was not activated by phosphatidylserine at Ca2+ concentrations corresponding to the intracellular free Ca2+ concentration under resting conditions. However, at similar Ca2+ concentrations (less than 2.5 X 10(-7) M) the enzyme was highly activated by phorbol 12-myristate 13-acetate (PMA) or diolein in the presence of phosphatidylserine. It was demonstrated that PMA stimulation of human polymorphonuclear leukocytes did not induce any increase in the level of the intracellular free calcium concentration. It was concluded that PMA activation of protein kinase C occurred independently of a rise in the intracellular Ca2+ concentration. K0.5 (half-maximal activation) for the PMA activation of purified protein kinase C was shown to be equivalent to the K0.5 for PMA stimulation of superoxide (O-2) production in human polymorphonuclear leukocytes, suggesting that protein kinase C is involved in activation of the NADPH oxidase. The presumed intracellular Ca2+ antagonist TMB-8 inhibited the PMA-induced superoxide production, but neither by an intracellular Ca2+ antagonism nor by a direct inhibition of protein kinase C activity.

Animals↗
PubMed2000

Interactions of alcuronium, TMB-8, and other allosteric ligands with muscarinic acetylcholine receptors: studies with chimeric receptors.

A series of ligands that allosterically modulate the binding of classical ligands to muscarinic receptors was evaluated at wild-type and chimeric receptors. All of the ligands studied had highest affinity toward the M(2) subtype and lowest affinity toward the M(5) subtype. The chimeric receptors were mostly M(5) sequence; the amount of M(2) sequence ranged from about 6 to just under 30%. Alcuronium and TMB-8 had much higher affinity for the chimeric receptor that included the M(2) second outer loop of the receptor plus flanking regions of TM4 and TM5 than for any of the other chimeric receptors (the affinities of which remained similar to that of the M(5) subtype). However, this chimera retained the negative cooperativity between alcuronium and the classical antagonist N-methylscopolamine that is characteristic of M(5) (these ligands are positively cooperative at M(2)). Verapamil, tetrahydroaminoacridine, and d-tubocurarine were also sensitive to that chimeric substitution, although verapamil and tetrahydroaminoacridine had even higher affinity for a chimera with M(2) sequence in TM7. None of these ligands shared gallamine's sensitivity to a region of the third outer loop, but studies in which obidoxime reversed the allosteric effects of gallamine and other ligands suggested that they nevertheless compete for a common site. In summary, although the present data are consistent with previous studies that have suggested that allosteric ligands bind to the outermost regions of muscarinic receptors, it appears that different allosteric ligands may derive subtype selectivity from different regions of the receptor.

Acetylcholine↗
PubMed1976

[Proposal of a new procedure for the exploration of hepatocellular function. The trimethoxybenzene test (TMB)].

The authors propose a new method of exploration of liver cell function based on the study of demethylation of a rapidly assimilated atoxic compound, trimethoxybenzene (TMB) in dimethoxy-hydroxybenzene (DMHB). Whereas in normal subjects, the urinary excretion of the metabolites was rapid and marked, 180 mg within 3 hours after taking a 400 mg dose, in patients with liver cell failure, the excretion of DMHB was considerably reduced, 80 to 95% in cirrhosis.

Benzene Derivatives↗
PubMed1979

[Changes in the transverse striated musculature during treatment with the pesticide, Neguvon, and TMB-4 reactivator].

The authors found that the contractile activity of isolated myofibers as-well as superprecipitation of myosin B were reduced after intoxication of white rats with 1/2 of dose of LD50 of neguvon. The reaktivator of cholinesterase TMB-4 (20 mg/kg) recovered the contractile capability of myofibres even on the third day after treatment, but superprecipitation of myosin B-after the twentieth day.

Animals↗
PubMed1981

[On the effect of imipramine on blood composition, glucose level and alkaline phosphatase activity of leucocytes in non-emotive Wistar rats and animals of inbred TMB strain (author's transl)].

The acute effect of imipramine (Tofranil) on the composition of blood, blood sugar level and activity of alcaline phosphatase in leucocytes was studied in an experiment with 30 adult male TMB-rats. These findings were compared with those in non-emotive Wistar rats (the scores without stress and under the condition of psycho-pharmacological effects) as far as corresponding motor activity in both strains was concerned. Hematological findings in a non-stress condition are considered to be identical in both strains studied. Under the acute effect of imipramine only about 50% of the compared parameters are similar to each other. The differing course of the hematological reaction within the other 50% points to the presence of non-identical control mechanisms in both strains.

Alkaline Phosphatase↗
PubMed1976

[Antidotal effect of TMB-4 compos. Spofa in sheep intoxicated with O-ethyl S-(2-dimethylaminoethyl) methyl phosphonothioate].

A single application of a mixture of cholinolytic and reactivator of cholinesterase (TMB-4 compos. SPOFA) administered intravenously in the dose of 10.0 mg of trimedoxim per kg of live weight to sheep for 60 minutes after an intramuscular intoxication with O-ethyl S-(2-dimethylaminoethyl) methyl phosphonothioate (EDMM) in the dose of 0.00835 mg per kg of live weight (i.m. LD50, 2h) produces an immediate clinical effect. The reactivation of the erythrocytary acetyl cholinesterase (AChE, E.C.3.1.1.7.) examined in 15 minutes after the administration of the antidotal mixture is almost 100 p.c., the reactivation of the plasmatic butyryl cholin esterase (ChE, E.C.3.1.1.8.) approx. from 70 to 80 p. c. Restitution ad integrum occurred not later than in 14 days after the intoxication.

Animals↗
PubMed1997

Stability of mono- and bisbenzyloxime ethers of the acetylcholinesterase reactivator TMB-4.

Mono- and bisbenzyloxime ethers of the bispyridinium derivative TMB-4 (UNO, DUO) are potent allosteric modulators of the muscarinic receptor attracting clinical interest in case of organophosphate poisoning. In order to work out the stability of these compounds oximes, different oxime ethers and potential degradation products were synthesized and UV- and NMR-spectroscopically characterized. The process of degradation of all compounds was observed under stress conditions at varying pH-values and different temperatures by means of time-dependent NMR- und UV-measurements. The pyridinium aldoxime turned out to be rather stable, whereas the oxime ether and cyano derivatives convert to the pyridone at high pH-values and high temperature. The mechanism of degradation is discussed.

Cholinesterase Reactivators↗
PubMed1983

Corticotectal terminals in the superior colliculus of the rabbit: a light- and electron microscopic analysis using horseradish peroxidase (HRP)-tetramethylbenzidine (TMB).

The projection from the striate cortex to the superior colliculus was studied light- and electron microscopically by means of anterogradely transported horseradish peroxidase and tetramethylbenzidine histochemistry. Labeled boutons were found in the stratum zonale (SZ) and in the stratum griseum superficiale (SGS), not in stratum opticum (SO). There are two maxima of frequency of labeled boutons, one in middle SGS at about 500 microns depth, and a smaller one in upper SGS at about 200 microns depth. Such a bimodal distribution of corticotectal terminals has not been described in any species before. Labeled myelinated axons were found in SGS and SO with a maximal frequency in middle SGS at about 400 microns depth. The myelinated axons in SZ, which are commonly considered to be of cortical origin, were not labeled. The labeled cortical terminals contained numerous round synaptic vesicles and predominantly dark mitochondria. They formed usually asymmetrical synapses and contacted dendrites, some of which contained synaptic vesicles. Occasionally, labeled boutons were observed which definitely did not belong to the type that is generally considered to be of cortical origin.

Animals↗
PubMed1980

An anterogradely-labeled prefrontal cortico-oculomotor pathway in the monkey demonstrated with HRP gel and TMB neurohistochemistry.

Implants of horseradish peroxidase gel6 in the sulcus principalis and/or area 8 "frontal eye field" cortex of macaque and cebus monkeys, processed with tetramethyl benzidine (TMD) neurohistochemistry9, resulted in anterograde labeling of a prominent "prefrontal oculomotor bundle" which traversed the medial subthalamic region at the diencephalic-mesencephalic junction to terminate directly in accessory and principal oculomotor nuclear groups. This report provides clear evidence suggesting direct cortical involvement in ocular motility, and the location of the pathway contributes to our understanding of ophthalmoplegias resulting from lesions in the rostralmost mesencephalon.

Animals↗
PubMed1981

On retro- and anterograde transport of horseradish peroxidase in the pontocerebellar fibers as studied with the Mesulam TMB technique.

In cats where injections of HRP have been made in the cerebellar cortex, pontocerebellar fibers are visualized throughout their length. Likewise, injections of HRP into the pontine nuclei visualize the pontocerebellar fibers and these anterogradely stained axons can in fortunate sections be followed into the granular layer. A visualization of retrogradely filled pontocerebellar fibers was unexpected and its another example of the sensitivity of the Mesulam8 technique.

Afferent Pathways↗