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At least 19 recordsLinked to original sources
PubMed1979

Activation of the frog sartorius acetylcholine receptor by a covalently attached group.

The frog sartorius motor endplate was treated with the specific disulfide bond reducing agent dithiothreitol and subsequently exposed to a covalently reacting compound (the nitrophenyl ester of p-carboxyphenyltrimethylammonium iodide, NPTMB) known to activate the dithiothreitol-reduced acetylcholine receptor in Electrophorus electroplax. NPTMB causes a maximum depolarization of about 35 mV when applied to the dithiothreitol-treated sartorious motor endplate. It is ineffective on postjunctional membrane prior to disulfide bond reduction and on extrajunctional regions, reduced or unreduced. High concentrations of a competitive antagonist such as (+)-tubocurarine prevent reaction between NPTMB and the reduced receptor and cause a repolarization of the membrane when applied to the already-depolarized preparation. We conclude that in frog muscle, as in electroplax, the attached activator bridges the acetylcholine binding site of the reduced receptor between a sulfhydryl group, to which it is covalently bound, and a negative subsite, with which it forms a reversible ionic band.

Acetylcholine↗
PubMed1978

Guinea pig immunoglobulin light chain isotypes. II. The preferential expression of lambda chain-bearing anti-phenyltrimethylammonium antibodies is associated with restricted variable region expression, but not with any alteration in the proportion of lambda chain constant region isotypes, relative to normal immunoglobulins.

The inbred strain 13 guinea pig expresses at least three isotypes of immunoglobulin (Ig) lambda chain. The proportion of these isotypes in normal Ig can be estimated by isolating a constant (C) region cyanogen bromide peptide from lambda chains and quantitatively analyzing its component tryptic peptides. Anti-phenyltrimethylammonium antibody, when analyzed in this way, was found to contain the same proportion of each lambda chain C region isotype as did normal Ig. The specific antibody light (L) chain pools were found to contain predominantly lambda chains, although these are the minority type in guinea pig normal Ig L chain pools. Moreover, amino-terminal, 5-pyrrolidone-2-carboxylic acid-containing peptides isolated from antibody lambda chains show no demonstrable sequence heterogeneity, while their homologs isolated from normal lambda chains are markedly heterogeneous. That a restriction in heterogeneity of variable region framework residue positions is not associated with any alteration in the proportion of C region isotypes in these antibody lambda chains, implies that translocation of all guinea pig lambda chain variable region genes to the isotypic C region genes occurs in a random way.

Animals↗
PubMed1979

Voltage fluctuations at the frog sartorius motor endplate produced by a covalently attached activator.

The depolarization that develops after covalent attachment of trimethylammonium benzoyl to the dithiothreitol-reduced frog sartorius acetylcholine receptor is accompanied by a small increase in voltage fluctuations. The amplitude of the elementary voltage event produced by the covalently attached activator is about 0.04 microV, almost an order of magnitude below the acetylcholine shot-effect amplitude in the control preparation, and about one-fourth the acetylcholine shot amplitude after disulfide-bond reduction. Spectral density plots of trimethylammonium-benzoyl noise can be analyzed in terms of two relaxation rates that bracket the single rate observed in response to acetylcholine.

Acetylcholine↗
PubMed1977

Selective electrode for dibenzyl dimethyl ammonium cation as indicator of the membrane potential in biological systems.

The electrode sensitive to dibenzyl dimethyl ammonium (DDA+), which is considered to be an indicator of the membrane potential, was constructed by using tetraphenyl borone (TPB-) embedded in dichloroethane. Rapid and Nernstian responses were exhibited against DDA+ solutions ranging between 10(-2) and 3 - 10(-6) M in concentration. High selectivity for DDA+ was observed in the presence of various inorganis salts, ADP, ATP, oxidizable substrates and sugars. The electrode developed here was used to measure the DDA+ uptake in Streptococcus faecalis and the results agreed with those reported by Harold, F.M. and Papineau, D. ((1972) J. Membrane Biol. 8, 27-44 and 45-62). While they determined the DDA+ concentration in the medium by measuring the absorbance of the filtrate treated with the ion-exchangers, the electrode can measure directly the DDA+ concentration in the bacterial suspension without any any pretreatment. It was also shown that the electrode can measure the DDA+ uptake in mitochondria during energization.

Animals↗
PubMed1976

Binding of ampholine to transfer RNA.

The melting temperature of isoaccepting tRNAfMet is affected by Ampholine. The plot of Tm versus the logarithm of Ampholine concentration shows clearly an increasing effect of Ampholine when the pH changes from 7.4 to 4.2. This result is interpreted as binding of Ampholine to the nucleic acid. The effects of Ampholine have been compared with those of soidum, magnesium and tetraethylene pentamine. Ampholine carrier ampholytes at pH 4.2 bind to tRNA with the same affinity as magnesium; at higher pH values they are less active. An hypothesis for the mechanism of action of Ampholine on nucleic acids during isoelectric focusing is proposed.

Bis-Trimethylammonium Compounds↗
PubMed1979

Transmembrane electrical potential and transmembrane pH gradient in the acidophile Thiobacillus ferro-oxidans.

Thiobacillus ferro-oxidans is capable of using the oxidation of Fe2+ by O2 at pH 2.0 as the sole source of energy for growth and CO2 fixation. The bacterium maintains an intracellular pH of 6.5 over a range of external pH from 1.0 to 8.0, as measured by [14C]acetate and [3H]methylamine distribution. The membrane potential was estimated by the distribution of the lipid-soluble cation dibenzyldimethylammonium and the anion SCN-. At pH 2.0 (the pH of growth) during Fe2+ oxidation the transmembrane pH gradient is 4.5 units with an opposing membrane potential of -10mV, giving a proton electrochemical gradient of +256mV. This gradient is actively maintained.

Bis-Trimethylammonium Compounds↗
PubMed1975

Interaction of competitive antagonists: the anti-curare action of hexamethonium and other antagonists at the skeletal neuromuscular junction.

1. In the rat isolated diaphragm preparation hexamethonium and other low potency competitive antagonists of acetylcholine (ACh), including gallamine and hyoscine butylbromide, reverse block by the potent antagonists tubocurarine, pancuronium and alcuronium. 2. In the presence of tubocurarine, hexamethonium increases the amplitude of the end-plate potential without increasing the quantal content. It enhances the response to ACh applied iontophoretically to the end-plate but does not enhance the response to ACh applied in the bath. 3. The anti-curare effect of hexamethonium is abolished in the diaphragm of the rat, guinea-pig and mouse by inhibitors of acetylcholinesterase. The effect is not observed in the indirectly stimulated toad sartorius muscle. 4. The effect is explained if tubocurarine does not dissociate appreciably in the time taken for ACh to achieve high occupancy of receptors, so that a fraction of receptors is completely excluded from occupation by ACh. Equilibration with hexamethonium reduces the fraction excluded by tubocurarine and the transmitter now competes with hexamethonium for more receptors and produces a larger response. 5. On the basis of this explanation the half-time for dissociation of tubocurarine must be about 1 millisecond. It follows that tubocurarine does not act competitively with ACh at synapses when transmitter action is sufficiently brief, and that its binding to the receptor is probably diffusion-limited.

Acetylcholine↗
PubMed1979

Induced hypotension for orthognathic surgery.

Achieving satisfactory hemostasis during orthognathic surgery may be difficult because of the extensive vascularity of facial structures. Hypotensive anesthetic techniques provide clear operative fields by altering regional tissue perfusion through the use of systemic vasodilators, ganglionic blocking agents, and positioning of the patient. Thorough monitoring during surgery, careful selection of patients, and close communication between the surgeon and anesthesiologist permit safe anesthesia, can decrease operating time, and usually obviate the need for transfusions.

Adult↗
PubMed1979

[Clinical use of arfonad and hygronium aerosols in emergency hypotensive therapy].

During clinical testing of the administration of ganglion-blocking agents by inhalation (175 persons) it was established that drug aerosols of arfonad and hygronium possess high effectiveness, act rapidly, and are relatively safe. The inhalation method of the management of hypertensive crises may find wide use in out-patient practice, under conditions of the admission room, cardiological and resuscitation departments, as well as in obstetrics when controlled hypotension is necessary.

Adult↗
PubMed1979

[Transplantability and growth of sarcoma 37 under a ganglionic blockade].

The inoculation of sarcoma-37 against the background of the ganglionary blockade, provided by the intraperitoneal injection of 1 ml of pentamine, is not associated with its less take rate, but there is a manifest suppression of the tumor growth during the period up to 63 days. A preliminary ganglionary blockade completely eliminates the stimulating effect of a trauma on the tumor growth.

Amputation, Surgical↗
PubMedDate not supplied

[Study of skeletal muscle cholinoreceptors using alkylating agents].

The ability of decamethonium containing beta-clorethylamino groups to alkylate the nicotinic cholinoreceptors of the frog tonic muscles was studied. D-tubocurarine prevented the action of the alkylating decamethonium (AD). The latter equally inhibited the effects of carbacholine and tetramethylammonium. The degree of alkylation did not change with pH varying from 6 to 11. AD did not produce any parallel shifts, but inhibited at once the maximal response to carbacholine both of the frog intact muscle and of a single tonic fibre. It is suggested that decamethonium blocks the cholinoreceptors anionic sites, which are represented by the carboxylate, or phosphate anions. The frog tonic muscle probably fails to posses any spare receptors.

Alkylation↗