The effects of m-octopamine on salivary flow rates and protein secretion by rat submandibular glands

1. m-Octopamine given i.v. or i.p. was a potent sialogogue for rat salivary glands.2. Salivation in response to i.v. m-octopamine was completely abolished by prazosin and phenoxybenzamine.3. The α-type of proteins were secreted in response to all doses of i.v. and i.p. m-octopamine and these were converted into the β-type with prazosin, but not with yohimbine.4. m-Octopamine stimulated both α- and β-adrenoceptors and was a much more selective α₁-agonist than was the p-isomer.     

Analysis of biogenic amines in plasma of hypertensive patients and a control group

Procedures were developed for the determination of 17 circulating amines using gas chromatography-negative ion chemical ionisation mass spectrometry. The amines were quantified against their appropriate deuterated isotopomers. The mean concentrations and ranges of catecholamines and trace amines were high compared with previous studies. In comparison with nonhypertensives, plasma from hypertensives had higher concentrations of the following amines: noradrenaline (t=4.0%); normetanephrine (t=6.1%) and metanephrine (t=1.9%). There were no significant differences between 5HT levels in plasma from hypertensives and controls. The following trace amine could be detected in variable amounts in plasma:p-tyramine,m-tyramine,p-octopamine,m-octopamine,p-synephrine,m-synephrine, and salsolinol. The trace amines melatonin,N-acetyl 5HT, tryptamine, 6-hydroxymelatonin and 5-methoxytryptamine could not be detected in plasma with limits of detection lying in the range 20–100 pg ml^–1.     

Octopamine metabolism in the cephalic ganglion of Locusta migratoria L.

Octopamine contents in the cephalic ganglia of the locust Locusta migratoria have been determined in male and female late larval and in adult stages. The animals have been pretreated with intra-abdominal administration of p-tyrosine or p-tyramine alone or following the administration of reserpine.1. p-Octopamine levels were higher at the 7th day than at the 5th day in the fourth larval stage. At this stage a significant difference was observed in male and female cephalic ganglia.2. The administration of p-tyrosine and p-tyramine resulted in ganglia.3. The pretreatment with reserpine resulted in an almost complete depletion in p-octopamine.4. This depletion was partially abolished by p-tyrosine or more efficiently by p-tyramine administration.5. Eventually, the p-octopamine levels were considerably decreased by the administration of the decarboxylase inhibitor, R04-4602, of the dopamine β-hydroxylase inhibitor, fusaric acid, and of the false neurotransmitter 6-hydroxydopamine.     

m-Octopamine as a substrate for monoamine oxidase.

$\text{m}$-Octopamine was characterized as substrate for monoamine oxidase (MAO) in rat brain and liver mitochondria. The $\text{K}$m and $\text{V}$max values of the brain enzyme were 735 μM and 32.5 nmoles/mg protein/30 min, and those of the liver enzyme 351 μM and 125 nmoles/mg protein/30 min, respectively. The inhibition experiments with clorgyline and deprenyl showed that $\text{m}$-octopamine was a common substrate for type A and type B MAO, though a major part of the activity was due to type A enzyme.     

Partial characterization of N-acetyltransferase activity from cerebral ganglia and malpighian tubules of Periplaneta americana

Octopamine-N-acetyltransferase (NAT) activity from Malpighian tubules and cerebral ganglia of Periplaneta americana was studied using high performance liquid chromatography with coulometric electrochemical detection. The enzyme from these tissues is highly soluble and temperature-resistant with maximal activity demonstrated at 50°C. The pH profiles of enzyme activity from Malpighian tubules and cerebral ganglia differ markedly although, in both tissues, strong activity is evident under alkaline conditions. Kinetic analyses indicate that the enzyme present in Malpighian tubules has a K_m for octopamine of 0.40 mM with a maximum velocity of 37.9 nmol N-acetyl-p-octopamine (N-acOA) produced/mg protein/min; the equivalent values for acetyl CoA were determined as 0.32 mM and 36.9 nmol N-acOA/mg protein/min. NAT from cerebral ganglia showed K_ms for octopamine and acetyl CoA of 0.33 and 0.19 mM, respectively, and the maximum velocity with octopamine was 6.8 nmol N-acOA/mg protein/min. Analysis of NAT activity from a variety of cockroach tissues indicates that the enzyme is widely distributed, with the gut and associated Malpighian tubules, conglobate gland and salivary glands showing the greatest activity.     

Effects of Aging on p- and m-Octopamine, Catecholamines, and Their Metabolizing Enzymes in the Rat

Abstract: Functions of octopamine in the mammalian brain are still not well known. An important aspect of this problem is the relationship between octopamines and catecholamines. Previous data have shown that their respective ontogenic evolutions are not parallel. Do the changes in brain related to aging also differentially affect these two groups of molecules? In order to check this point, the brain levels of p- and m-octopamine, p-tyramine, noradrenaline, and dopamine, as well as the activities of metabolizing enzymes, were determined in young adult and aging rats (20–26 months). Unlike catecholamines, there is a drastic decrease of p-octopa-mine after 20 months of age in the hypothalamus and telencephalon. p-Tyramine levels are also lowered. This change appears to be due to a decrease of the aromatic L-amino acid decarboxylase activity. These data, as those of ontogenic studies, confirm that p-octopamine and catecholamine metabolisms may have some independent steps and, moreover, that p-octopamine may have a role in the normal activity of the brain.     

The chemotactic activity of various sirenins and analogues and the uptake of sirenin by the sperm of allomyces

Optimal response of the sperm of Allomyces from the highly male strain M16 to the chemotactic agent, sirenin, was shown to occur when the sperm suspension contained 2 mm piparazine-N′, N-bis[2-ethane sulfonic acid] buffer, 3 mm CaCl₂, and chelated trace elements. For the male strain M3, the CaCl₂ needed was 3.5 mm with the other two components the same as for M16. The inclusion in the sperm suspension of MgCl₂, KH₂PO₄, or NH₄Cl was without effect, except that under certain conditions phosphate was detrimental. The variability of 10 replicate assays was substantially reduced by using sperm in the bioassay at a concentration of 500,000 per ml rather than the former concentration of 100,000 per ml with a concomitant reduction in the concentration of sirenin above the membrane to which the sperm were attracted.     

Characterization of a potent agonist of the insect octopamine-receptor-coupled adenylate cyclase

The imidazoline, 2,3-xylylaminomethyl-2′-imidazoline (XAMI) was evaluated for its effects on octopamine-sensitive adenylate cyclase (OSAC) in crude membrane preparations of neural and non-neural tissues of the American cockroach, Periplaneta americana and ventral-nerve cord homogenates of the tobacco hornworm, Manduca sexta. In the cockroach nerve cord, XAMI was found to be a partial agonist with a V_max 80% of p-octopamine (OA) and a K_a of 30 nM. The affinity is 185 times greater than that of OA. Additivity studies suggest that at maximally stimulating concentrations, XAMI interacts primarily with the OSAC. The antagonist profile for XAMI mimics that of OA with mianserin being the best antagonist, followed by the α-adrenergic antagonist phentolamine. These antagonists were shown to act competitively at the XAMI-binding site. β-adrenergic and dopaminergic antagonists were ineffective. These data indicate that XAMI has the highest reported affinity of any OA-receptor agonist and may be a suitable ligand for studies of the OA receptor.     

The effect of ethanol on drug oxidations in vitro and the significance of ethanol-cytochrome P-450 interaction

The effect of ethanol on N-demethylation of aminopyrine in rat liver slices and in the microsomal fraction and on microsomal hydroxylation of pentobarbital and aniline was studied. With liver slices N-demethylation of aminopyrine was stimulated by 35–40% at low ethanol concentrations (2mm), whereas no stimulation occurred at high concentrations (100mm). With the liver microsomal fraction, an inhibitory effect was observed only at high ethanol concentrations (100mm). This was also observed with the other drugs studied. In agreement with these results, only at a high concentration did ethanol interfere with the binding of drug substrates to cytochrome P-450. Further, as previously reported, ethanol produced a reverse type I spectral change when added to the liver microsomal fraction. Evidence that this spectral change is due to removal of substrate, endogenously bound to cytochrome P-450, is reported. A dual effect of ethanol is assumed to explain the present findings; in liver slices, at a low ethanol concentration, the enhanced rate of drug oxidation is the result of an increased NADH concentration, whereas the inhibitory effect observed with the microsomal fraction at high ethanol concentration is due to the interference by ethanol with the binding of drug substrates to cytochrome P-450.     

Effects of ethanol concentration on immobilized Zymomonas mobilis for continuous production of ethanol

The effects of ethanol concentration on the ethanol productivity and activity of immobilized Zymomonas mobilis cells during continuous fermentation of glucose has been studied at various ethanol concentrations. On changing the inlet ethanol concentration, Po, from 0.0 kg/m³ to any other level, 8 h were required to fully experience the effects of a change in Po, whereas 8 h to 2 days, depending on Po, were required to reach the steady state on switching back to the ethanol free medium. The volumetric ethanol productivity decreased from 92.5 to 0.0 kg/m³·h as the ethanol concentration in the bioreactor was changed from 46.3 to 126 kg/m³. The activity of the immobilized cells recovered up to 63% in 2 days even after exposing the cells to 126 kg/m³ of ethanol.     

Metabolism of inorganic sulphate in the isolated perfused rat liver. Effect of sulphate concentration on the rate of sulphation by phenol sulphotransferase

1. The metabolism of inorganic [³⁵S]sulphate (Na₂³⁵SO₄) was studied in the isolated perfused rat liver at three initial concentrations of inorganic sulphate in the perfusion medium (0, 0.65 and 1.30mm), in relation to sulphation and glucuronidation of a phenolic drug, harmol (7-hydroxy-1-methyl-9H-pyrido[3,4-b]indole). 2. [³⁵S]Sulphate rapidly equilibrated with endogenous sulphate in the liver. It was excreted in bile and reached, at the lowest concentration in the perfusion medium, concentrations in bile that were much higher than those in the perfusion medium; at the higher sulphate concentrations, these concentrations were equal. The physiological concentration of inorganic sulphate in the liver, available for sulphation of drugs, is similar to the plasma concentration. 3. At zero initial inorganic sulphate in the perfusion medium, the rate of sulphation was very low and harmol was mainly glucuronidated. At 0.65mm-sulphate glucuronidation was much decreased and considerable sulphation took place, indicating efficient competition of conjugation by sulphation. At 1.30mm-sulphate the sulphation increased still further. 4. The results suggest that an important factor in sulphation is the relatively high K_m of synthesis of adenosine 3′-phosphate 5′-sulphatophosphate (the co-substrate of sulphation) for inorganic sulphate, which is of the order of the plasma concentration of inorganic sulphate. The steady-state adenosine 3′-phosphate 5′-sulphatophosphate concentration may determine the rate of sulphate conjugation of drugs in the rat in vivo.     

Investigation of the subcellular distribution of cyclic-AMP phosphodiesterase in rat hepatocytes,using a rapid immunological procedure for the isolation of plasma membrane

The distribution of cyclic-AMP phosphodiesterase was investigated in subcellular fractions prepared from homogenates of rat liver or isolated hepatocytes. When measured at 1 mM or 1 μM substrate concentration, approx. 35% or 50%, respectively, of enzyme activity was particulate. The soluble activity appeared to be predominantly a ‘high K_m’ form, whereas the particulate activity had both ‘high K_m’ and ‘low K_m’ components. The recovery of cyclic-AMP phosphodiesterase was measured using 1 μM substrate concentration, in plasma membrane-containing fractions prepared either by centrifugation or by the use of specific immunoadsorbents. The recovery of phosphodiesterase was lower than that of marker enzymes for plasma membrane, and comparable with the recovery of markers for intracellular membranes. It was concluded that regulation of both ‘high K_m’ and ‘low K_m’ phosphodiesterase could potentially make a significant contribution to the control of cyclic AMP concentration, even at μM levels, in the liver. The ‘low K_m’ enzyme, for which activation by hormones has been previously described, appears to be located predominantly in intracellylar membranes in hepatocytes.The immunological procedure for membrane isolation allowed the rapid preparation of plasma membranes in high yield. Liver cells were incubated with rabbit anti-(rat erythrocyte) serum and homogenized. The antibody-coated membrane fragments were then extracted onto an immunoadsorbent consisiting of sheep anti-(rabbit IgG) immunoglobulin covalently bound to aminocellulose. Plasma membrane was obtained in approx. 40% yield within 50 min of homogenizing cells.     

Characterization of glutamate transport system in hydrophobic protein (H protein) of Bacillus subtilis

Hydrophobic protein (H protein) was isolated from membrane fractions of Bacillus subtilis and constituted into artificial membrane vesicles with lipid of B. substilis. Glutamate was accumulated into the vesicle when a Na⁺ gradient across the membrane was imposed. The maximum effect of Na⁺ on the transport was achieved at a concentration of about 40 mM, while the apparent K_m for Na⁺ was approximately 8 mM. On the other hand, K_m for glutamate in the presence of 50 mM Na⁺ was about 8 μM. Increasing the concentration of Na⁺ resulted in a decrease in K_m for glutamate, maximum velocity was not affected. The transport was sensitive to monensin (Na⁺ ionophore).Glutamate was also accumulated when pH gradient (interior alkaline) across the membrane was imposed or a membrane potential was induced with K⁺-diffusion potential. The pH gradient-driven glutamate transport was sensitive to carbonylcyanide m-chlorophenylhydrazone and the apparent K_m for glutamate was approximately 25 μM.These results indicate that two kinds of glutamate transport system were present in H protein: one is Na⁺ dependent and the other is H⁺ dependent.     

Reversible abolition of enhancement in isolated spinach chloroplasts

The photosynthetic evolution of oxygen by isolated chloroplasts of Spinacia oleracea L. was studied using a modulated oxygen electrode. The enhancement effect, measured as the increase in the relative quantum yield of 650-nanometer light due to the presence of 710-nanometer light, was profoundly influenced by the concentration of inorganic cations in the bathing medium. Chloroplast fragments immersed in a solution containing a very low concentration of MgCl₂ or KCl, did not display enhancement but could be made to do so by raising the concentration of MgCl₂ to 3 mm, or that of KCl to 35 mm. This change in the enhancement properties was completely reversible. The maximum value of enhancement in a MgCl₂ solution appeared to occur at a concentration between 15 and 30 mm, while in KCl, the enhancement effect increased almost linearly up to a concentration of 100 mm.     

MASS FRAGMENTOGRAPHY OF PHENYLETHYLAMINE, m- AND p-TYRAMINE AND RELATED AMINES IN PLASMA, CEREBROSPINAL FLUID, URINE, AND BRAIN

—A mass fragmentographic method for the assay of phenylethylamine (PEA) and a number of related amines in several biological materials is described. The gas chromatographic column employed for this analysis is a 12ft 1/8 in. o.d. steel column packed with 0.5% OV₂₂+ 2% SE54 + 1% OV₂₁₀ coated on 80/100 mesh chromosorb W (HP). The mass spectral characteristics of these amines are illustrated, compared, and discussed. Of the various monoamines which could be measured, only PEA, m- and p-tyramine were detected in measurable quantities. Phenylethanolamine and p-octopamine were found in trace amounts in urine, plasma, cerebrosponal fluid, and rat brain. No diurnal variation in the urinary excretion of PEA, m- and p-tyramine was observed. Plasma concentration of PEA or p-tyramine did not significantly change 1 h after eating a breakfast. Furthermore, consuming 200 g of Cadbury milk chocolate containing about 1 mg of PEA, 0.1 mg of phenylethanolamine and 10 mg of p-tyramine did not significantly alter urine excretions of these three amines. In the brain, as has been reported by others, we found that PEA and p-tyramine are not evenly distributed and that the highest concentrations are found in the hypothalamus and caudate. From the results obtained we concluded that PEA, m- and p-tyramine are probably produced from endogenous sources and that the direct contribution of diet to their urine excretion is small.     

In vitro plant regeneration, secondary metabolite production and antioxidant activity of micropropagated Aloe arborescens Mill

Aloe species are highly-prized for their ornamental value and have been utilized for centuries in traditional medicine. Due to their habitat loss and exploitation for medicinal and ornamental plant trade, many species in this genus have become threatened. One of the most important globally rated medicinal species in Aloe genus is A. arborescens. The current study evaluated the roles of different aromatic cytokinin types and concentrations on direct organogenesis, in vitro bioactive secondary metabolite production and antioxidant activity of regenerated shoots of A. arborescens. There was an increase in the number of adventitious shoots produced per explant with an increase in concentration in cultures treated with meta-topolin (mT), meta-topolin riboside (mTR), meta-methoxytopolin (MemT) and benzyladenine riboside (BAR), reaching an optimum at either 5.0 or 7.5???M. Overall, the treatment with 5.0???M mT gave the largest number of transplantable shoots (regenerated shoots with length greater than 10?mm). Rooted shoots were successfully acclimatized after 8?weeks with a survival frequency above 90?% and no observable morphological abnormalities. Variable amounts of total iridoids, phenolics, flavonoids and condensed tannins were detected in regenerated shoots from all the cytokinin treatments. An increased free-radical scavenging activity with an increase in concentration was recorded in regenerated shoots from mT and mTR treatments, reaching an optimum at 7.5???M concentration. The present study shows that the choice of cytokinin type and concentration exogenously supplied during tissue culture markedly influences not only shoot proliferation but also the in vitro production of bioactive secondary metabolites.     

Simultaneous extraction and separation of trace amines of biological interest

A method is described for the simultaneous extraction and separation of the trace amines 2-phenylethylamine, m-tyramine, p-tyramine, p-octopamine, normetanephrine, and 3-methoxytyramine. The method involves acetylation in aqueous solution, specific hydrolysis of phenolic acetate groups, derivatization with trifluoroacetic anhydride and analysis on a gas chromatograph equipped with an electron-capture detector. Analyses utilizing both packed glass columns and glass capillary columns are described.The method possesses the potential for quantitative as well as qualitative analysis, with one or more of the following amines employed as internal standards: benzylamine, 3-phenylpropylamine, tranylcypromine, and 2-(4-chlorophenyl)ethylamine.     

DSC — A Valuable Tool in Heterocyclic Synthesis

Many decomposition and ring closure reactions in the azide series (e.g. a cyclization and rearrangement reaction sequence from the azido ester 1 via the ethoxy oxazole 2 to the oxazolone 3), intramolecular rearrangement reactions (e.g. via a-oxoketenes), self condensation of p-octopamine and also reactions with two reactants and the influence of solvents at the reaction conditions were studied using DSC (Differential Scanning Calorimetry).     

Mean activity coefficients for the simple electrolyte in aqueous mixtures of polyelectrolyte and simple electrolyte. V. common counterion mixtures of alkali-metal dextransulfates with alkali metal chlorides

Mean molal activity coefficients of simple electrolyte in aqueous solutions of Li, Na, K or Cs salts of dextransulfate (DS) with added LjCl, NaCl, KCl or CsCl are reported. The measurements were carried out by means of an electrochemical cell method using a cation exchange membrane as cation selective electrode and Ag/AgCl electrodes. For LiDS-LiCl, NaDS-NaCl and CsDS-CsCl systems the polymer concentration, m_p, was varied from 0.0088 to 0.113 m and at a given m_p the ratio X of the polymer to salt concentration was varied from 0.5 to 16. Due to the insolubility of KDS in high concentration of KCl, the measurements on KDS-KCl system were performed in the m_p range of 0.0088–0.089 m and some of the smaller X values were omitted. The activity coefficient results are compared to Manning's limiting laws, the additivity rule, and to new limiting laws. The additivity rule can give an excellent representation of the data for all m_p values when γ_p is used as an adjustable parameter.     

A convenient analysis of Michaelis enzyme kinetic progress curves based on second derivatives

A simple method is described for the estimation of the Michaelis parameters, K_m and V_m, from a single progress curve at a single substrate concentration without the need to follow the reaction to completion. By measuring the substrate concentration and the time when the second derivative is at a minimum, K_m and V_m can be easily obtained.