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Pedrazza EL, Senger MR, Pedrazza L, Zimmermann FF, de Freitas Sarkis JJ, Bonan CD. Sertraline and clomipramine inhibit nucleotide catabolism in rat brain synaptosomes. Toxicol In Vitro 2007; 21:671-6. [PMID: 17317090 DOI: 10.1016/j.tiv.2007.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 01/04/2007] [Accepted: 01/05/2007] [Indexed: 11/22/2022]
Abstract
The effects of sertraline, a selective serotonin reuptake inhibitor, and clomipramine, a tricyclic antidepressant, were tested on ecto-nucleotidases from synaptosomes of cerebral cortex and hippocampus of rats. Sertraline and clomipramine (100-500 microM) inhibited NTPDase, but not ecto-5'-nucleotidase activity in both cerebral cortex and hippocampus. In cortical synaptosomes, sertraline inhibited both ATP and ADP hydrolysis in the concentrations tested. The inhibitory effect varied from 21% to 83% for ATP hydrolysis and 48% to 75% for ADP hydrolysis. The inhibition promoted by sertraline in hippocampal synaptosomes varied from 38% to 89% for ATP hydrolysis and 45% to 77% for ADP hydrolysis. A significant inhibition of cortical NTPDase activity by clomipramine was observed in the all concentrations tested (35-72% and 36-87% for ATP and ADP hydrolysis, respectively). Similar effects were observed in hippocampus (29-91% and 48-83% for ATP and ADP hydrolysis, respectively). There was no inhibitory effect of sertraline and clomipramine on AMP hydrolysis in cerebral cortex and hippocampus. Our results have shown that classical antidepressants inhibit the extracellular catabolism of ATP. Therefore, it is possible to suggest that changes induced by antidepressants on bilayer membrane could affect NTPDase activities and consequently, modulating ATP and adenosine levels in the synaptic cleft.
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Affiliation(s)
- Eduardo Luiz Pedrazza
- Laboratório de Neuroquímica e Psicofarmacologia, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul., Avenida Ipiranga, 6681, 90619-900, Porto Alegre, RS, Brazil
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Zanatta LM, Nascimento FC, Barros SV, Silva GR, Zugno AI, Netto CA, Wyse AT. In vivo and in vitro effect of imipramine and fluoxetine on Na+,K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats. Braz J Med Biol Res 2001; 34:1265-9. [PMID: 11593300 DOI: 10.1590/s0100-879x2001001000005] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+-ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients.
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Affiliation(s)
- L M Zanatta
- Departamento de Medicina Interna, Fundação Universidade do Rio Grande, Rio Grande, RS, Brasil
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Cestaro B. Effects of arginine, S-adenosylmethionine and polyamines on nerve regeneration. ACTA NEUROLOGICA SCANDINAVICA. SUPPLEMENTUM 1994; 154:32-41. [PMID: 7941963 DOI: 10.1111/j.1600-0404.1994.tb05407.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
INTRODUCTION Axon growth and axon regeneration are complex processes requiring an adequate supply of certain metabolic precursors and nutrients. MATERIAL AND METHODS This article reviews the studies examining some of the processes of protein modification fundamental to both nerve regeneration and to the continuous and adequate supply of specific factors such as arginine, S-adenosylmethionine and polyamines. RESULTS The process of arginylation notably increases following nerve injury and during subsequent regeneration of the nerve, with the most likely function of arginine-modification of nerve proteins being the degradation of proteins damaged through injury. It appears that defective methyl group metabolism may be one of the leading causes of demyelination, as suggested by the observation of reduced cerebrospinal fluid concentrations of s-adenosylmethionine (SAMe) and 5-methyltetrahydrofolate, the key metabolites in methylation processes, in patients with a reduction in myelination of corticospinal tracts. Polyamine synthesis, which depends strongly on the availability of both SAMe and arginine, markedly increases in neurons soon after an injury. This "polyamine-response" has been found to be essential for the survival of the parent neurons after injury to their axons. Polyamines probably exert their effects through involvement in DNA, RNA and protein synthesis, or through post-translational modifications that are indicated as the most relevant events of the "axon reaction." CONCLUSIONS Nerve regeneration requires the presence of arginine, s-adenosylmethionine, and polyamines. Further studies are needed to explore the mechanisms involved in these processes.
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Affiliation(s)
- B Cestaro
- Department of Biological Chemistry, University of Milan School of Medicine, Italy
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Viola MS, Bojorge G, Rodriguez de Lores Arnaiz G, Enero MA. Stimulation of Na+,K+-ATPase activity in certain membranes of the rat central nervous system (CNS) by acute administration of desipramine (DMI). Cell Mol Neurobiol 1989; 9:263-71. [PMID: 2545351 DOI: 10.1007/bf00713033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. The activities of ATPase in rat CNS were studied 3 hr after administration of the noradrenaline uptake inhibitor, desipramine (DMI: 10 mg.kg-1, i.p.). Na+K+-ATPase activity significantly increased after DMI in the whole particulate from hypothalamus and mesencephalus but no changes in frontal cortex or in pons-medulla oblongata areas were found. This increase was prevented when the animals were pretreated with the noradrenergic neurotoxic N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). 2. Purified membrane fractions from hypothalamus were obtained by differential and sucrose gradient centrifugation (0.8-1.2 M sucrose). It was observed that after DMI, Na+,K+-ATPase activity increased only in the membranous fraction lying at 0.9 M sucrose. 3. Mg2+- or Ca2+-ATPase activities were not modified by DMI treatment. 4. Citalopram, a specific serotonergic uptake inhibitor, did not affect ATPase activities. 5. The results obtained could indicate that DMI acute administration selectively stimulates Na+,K+-ATPase activity of certain membranes of the CNS after an increase in the concentration of the noradrenergic neurotransmitter in the synaptic gap.
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Affiliation(s)
- M S Viola
- Cátedra de Farmacología-Facultad de Farmacia y Bioquímica, UBA, Argentina
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Affiliation(s)
- F Schuber
- Laboratoire de Chimie Enzymatique Université Louis Pasteur, Institut de Botanique, Strasbourg, France
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Gentile V, Esposito C, Fusco A, Popoli M, Porta R. Spermine binding to subsynaptosomal fractions of rat brain cortex. Neurochem Res 1988; 13:369-76. [PMID: 3393265 DOI: 10.1007/bf00972487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Binding sites for [14C]spermine have been identified in rat brain cortex subcellular fractions. The binding, characterized by using synaptosomal membranes, is specific for spermine. It was not detected below 20 degrees C and increased about three/four-fold with a temperature rise of 10 degrees C. Binding occurred only in the presence of -SH reducing agents. It was completely suppressed by metal chelating agents, and was stimulated about four-fold by 1-5 x 10(-5) M Fe2+. Smaller increases were observed in the presence of Mn2+, Ni2+, Ca2+, Mg2+, and Zn2+; in contrast, millimolar concentrations of most divalent cations inhibited the binding differently (Mn2+ = Ni2+ = Zn2+ = Co2+ much greater than Mg2+ greater than Ca2+). Bound radioactive spermine was not displaced by the addition of high concentrations of unlabelled polyamine or chelating agents, nor by precipitation and washing of the membranes with 10 percent trichloroacetic acid, or by boiling of the precipitate in the presence of 1.0 percent SDS and 10 percent beta-mercaptoethanol. The trichloroacetic acid precipitate showed two radioactive bands, corresponding to low Mr (less than 8,000) components, after SDS-polyacrylamide gel electrophoresis and fluorography. The Fe2+-stimulated [14C]spermine binding was neither influenced by a previous heating of the membranes at 100 degrees C for 30 min nor by trypsin or pronase digestion, whereas the heat-treatment increased the binding occurring in the absence of Fe2+ by about two fold. A non-enzymatic formation of a spermine-metal complex tightly bound to some membrane peptide(s) is suggested.
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Affiliation(s)
- V Gentile
- Istituto di Chimica e Chimica Biologica, 1a Facoltà di Medicina e Chirurgia, Napoli, Italy
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Wood MD, Broadhurst AM, Wyllie MG. Examination of the relationship between the uptake system for 5-hydroxytryptamine and the high-affinity [3H]imipramine binding site--I. Inhibition by drugs. Neuropharmacology 1986; 25:519-25. [PMID: 3016589 DOI: 10.1016/0028-3908(86)90178-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The relationship between the binding site for imipramine and the uptake system for 5-hydroxytryptamine was examined. This was determined from the interaction between various drugs (including tricyclic antidepressants) and the high affinity accumulation of [3H]5-hydroxytryptamine in cortical synaptosomes from the rat, and with the high affinity binding of [3H]imipramine to cortical membranes of the rat. Imipramine and clomipramine, but not desipramine, were potent inhibitors of both binding of [3H]imipramine and the uptake of [3H]5-hydroxytryptamine. However, ouabain, panuramine and 5-hydroxytryptamine itself, all inhibited the binding of [3H]imipramine only at concentrations greater than those required to inhibit the uptake of [3H]5-hydroxytryptamine. Kinetic analysis revealed that inhibitors of the uptake system for 5-hydroxytryptamine produced inhibition by different mechanisms, but this did not account for their differential potency against uptake and binding. It is concluded that the binding site for [3H]imipramine and the uptake site for 5-HT are not directly linked and that drugs may inhibit the uptake of 5-HT at sites other than the binding site for [3H]imipramine.
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Law CL, Wong PC, Fong WF. Effects of polyamines on the uptake of neurotransmitters by rat brain synaptosomes. J Neurochem 1984; 42:870-2. [PMID: 6141227 DOI: 10.1111/j.1471-4159.1984.tb02761.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The influence of putrescine, spermidine, spermine, and some aliphatic alpha, w-diamines on the uptake spermine, and some aliphatic alpha, w-diamines on the uptake of neurotransmitters by rat forebrain synaptosomes was investigated. Choline uptake was most effectively inhibited by spermine (IC50 = 0.22 mM), less so by spermidine (IC50 = 4.0 mM), but not by putrescine (IC50 greater than 100 mM). At 10 mM, 1,3-diaminopropane, cadaverine, and 1,8-diaminooctane all inhibited choline uptake by 50% or more. Spermine and spermidine inhibited the uptake of dopamine with IC50 values of 2.7 and 2.2 mM, respectively. Putrescine was only slightly inhibitory (IC50 = 17.3 mM) and the other diamines were inactive. The uptake of gamma-aminobutyrate (GABA) was only slightly inhibited (15-40%) by the polyamines at 10 mM. With the exception of inhibition of glycine uptake by 1,8-diaminooctane (60%) and of glutamate uptake by cadaverine (35%) none of the polyamines, tested at 10 mM, affected the uptake of adenosine, glutamate, and glycine significantly. A possible modulatory role for polyamines in synaptic transmission through interaction by negatively charged groups of the synaptic membrane with the polycationic compounds is discussed.
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Oredsson SM, Friend DS, Marton LJ. Changes in mitochondrial structure and function in 9l rat brain tumor cells treated in vitro with alpha-difluoromethylornithine, a polyamine biosynthesis inhibitor. Proc Natl Acad Sci U S A 1983; 80:780-4. [PMID: 6402774 PMCID: PMC393463 DOI: 10.1073/pnas.80.3.780] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Mitochondrial structure and function were studied in 9L rat brain tumor cells depleted of polyamines by alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase. Cells treated with methylglyoxal bis(guanylhydrazone), a reversible inhibitor of S-adenosylmethionine decarboxylase, were used for comparison because this polyamine biosynthesis inhibitor is known to cause structural and functional disruption of mitochondria. A significant increase in mitochondrial size, measured quantitatively, was found in alpha-difluoromethylornithine-treated cells (10 mM for 72 hr) compared with untreated cells (P < 0.001). This increase in mitochondrial size was reversed when putrescine was added to the cultures for 24 hr after alpha-difluoromethylornithine treatment. Putrescine alone had no effect on the size of mitochondria. Treatment of cells with methylglyoxal bis(guanylhydrazone) (80 muM for 48 hr) caused only a slight increase in mitochondrial size compared with mitochondria in untreated cells (P < 0.05) and failed to produce the dramatic ultrastructural changes reported in other cell lines. Ultrastructural examination revealed an increase in cytoplasmic and membrane-associated ribosomes in alpha-difluoromethylornithine-treated cells, an increase in cytoplasmic ribosomes in methylglyoxal bis(guanylhydrazone)-treated cells, and an increase in membrane-bound ribosomes in putrescine-treated cells. In cells treated first with alpha-difluoromethylornithine and then with putrescine, the distribution of ribosomes was normal. The distributions of ribosomes were not quantitatively assessed. Pyruvate utilization, a measure of mitochondrial function, was decreased in cells treated with 10 mM alpha-difluoromethylornithine for 72 hr, compared with untreated cells. Restoration of intracellular polyamine levels by the addition of putrescine 24 hr before analysis reversed this phenomenon. Putrescine treatment alone did not affect pyruvate utilization. Pyruvate utilization in methylglyoxal bis(guanylhydrazone)-treated cells was depressed to a greater extent than that in alpha-difluoromethylornithine-treated cells.
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Rothwell NJ, Stock MJ, Wyllie MG. Sympathetic mechanisms in diet-induced thermogenesis: modification by ciclazindol and anorectic drugs. Br J Pharmacol 1981; 74:539-46. [PMID: 6271318 PMCID: PMC2071762 DOI: 10.1111/j.1476-5381.1981.tb10462.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
1 The sympathetic noradrenergic activation of brown adipose tissue and the biochemical mechanisms involved in diet-induced thermogenesis were studied in rats. 2 A close correlation was found between brown adipose tissue Na+, K+-adenosinetriphosphatase (Na+, K+-ATPase) activity in vitro and in vivo measurements of resting oxygen consumption (VO2). The effects of noradrenaline on in vitro NA+, K+-ATPase activity in brown adipose tissue and in vivo VO2 could be mimicked by a variety of agents. These included beta-adrenoceptor agonists and agents known to induce the release of noradrenaline or inhibit the noradrenaline uptake process. The pharmacological evidence suggests that dopaminergic mechanisms may also be involved in the control of thermogenesis. 3 Amphetamine did not increase VO2 in rats without causing associated increases in locomotor activity. Ciclazindol at doses of 3-30 mg/kg intraperitoneally increased VO2 but did not appear to increase locomotor activity or evoke any other signs of CNS stimulation including lengthening of time to sleep onset or stereotypy. Separation of metabolic and CNS effects occurred only at the lowest dose of mazindol used (0.3 mg/kg i.p.). These results are probably a reflection of (a) the relative abilities of these drugs to inhibit brain and brown adipose noradrenaline uptake processes and (b) the relatively high accumulation of ciclazindol in brown adipose. 4 Of the drugs tested, only ciclazindol was a more potent inhibitor of the noradrenaline uptake system in brown adipose tissue (BAT) than in brain. Kinetic analysis also revealed that the actions of ciclazindol on the NA uptake system and Na+, K+-ATPase in BAT differed from those of mazindol. 5 These findings suggest that ciclazindol may produce an energy wasting effect in rodents without causing overt CNS stimulation; the implications of these findings in terms of human obesity are discussed.
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Datta SC, Ghosh JJ. Effect of citreoviridin, a mycotoxin from Penicillium citreoviride, on kinetic constants of acetylcholinesterase and ATPase in synaptosomes and microsomes from rat brain. Toxicon 1981; 19:555-62. [PMID: 6460346 DOI: 10.1016/0041-0101(81)90014-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Gilbert JC, Wyllie MG. The relationship between nerve terminal adenosine triphosphatases and neurotransmitter release: as determined by the use of antidepressant and other CNS-active drugs. Br J Pharmacol 1980; 69:215-25. [PMID: 6108138 PMCID: PMC2044255 DOI: 10.1111/j.1476-5381.1980.tb07893.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
1 The role of adenosine triphosphatases (ATPases) in neurotransmitter release was studied using nerve terminals (synaptosomes) prepared from rat cerebral cortex as a model. 2 Amitriptyline, nortriptyline, protriptyline, desipramine and imipramine were found to inhibit ATPases at concentrations of 10(-5) M and above. The drugs inhibited both the basal and electrically evoked release of acetylcholine (ACh) and noradrenaline (NA) at concentrations of 10(-4) M and above. 3 At low concentrations of antidepressants (10(-8) and 10(-7) M) release of NA was enhanced but there was no effect on ACh release. 4 Other drugs which inhibit Na+, K+-ATPase increase basal NA release as did drugs which inhibited vesicular MG2+-ATPase. 5 A model is proposed suggesting that transmitter release/re-uptake depends on (1) active Na+, K+-ATPase at the presynaptic membrane and (2) an active synaptic vesicular MG2+-ATPase.
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Peter HW, Ahlers J, Günther T. The dependence of polyamine and phospholipid contents in maring bacteria on the osmotic strength of the medium. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1978; 9:313-6. [PMID: 668988 DOI: 10.1016/0020-711x(78)90103-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Tashima Y, Hasegawa M, Mizunuma H, Sakagishi Y. Specific effects of spermine on ouabain-sensitive and potassium-dependent phosphatase activity of kidney plasma membranes. Specificity of the potassium sites. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 482:1-10. [PMID: 193567 DOI: 10.1016/0005-2744(77)90347-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Specific inhibition of ouabain-sensitive and K+-dependent p-nitrophenyl-phosphatase activity of rabbit kidney plasma membranes by spermine (N,N'-bis(3-aminopropyl)-1,4-butanediamine) was characterized kinetically. 1. Inhibition by spermine was competitive with K+. The Ki for spermine was 31 micronM in the presence of 1 mM Mg2+. 2. Excess Mg2+ inhibited the ouabain-sensitive phosphatase activity in competition with K+. The Ki for Mg2+ was 2.6 mM. 3. Increasing Mg2+ concentrations reduced the spermine inhibition. This could be observed at Mg2+ concentrations higher than that of K+. 4. In the absence of inhibition by Mg2+, spermine was noncompetitive with Mg2+ which was essential for the ouabain-sensitive phosphatase activity. This could be observed at Mg2+ concentrations lower than that of K+. 5. Although Ca2+ was a strong inhibitor of the ouabain-sensitive phosphatase activity in the presence of K+, it produced a small stimulation of the activity in the absence of K+. Approximately 0.1 mM Ca2+ gave the maximum stimulation. 6. The observed Ca2+- and Mg2+-dependent phosphatase activity was inhibited strongly by ouabain and by spermine. The half-maximal inhibition concentrations of ouabain and spermine were 0.1 and 63 micronM, respectively. It is likely that Mg2+, Ca2+ and spermine bind to the same site as does K+.
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Fowler PD, MacNeill A, Spencer D, Robinson ET, Dick WC. Imipramine, rheumatoid arthritis and rheumatoid factor. Curr Med Res Opin 1977; 5:241-6. [PMID: 162660 DOI: 10.1185/03007997709110172] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Affiliation(s)
- I Farská
- Psychiatric Research Unit, Faculty of Medicine, Charles University, Prague 2, Ke Karlovu 11, Czechoslovakia
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Association of putrescine, spermidine, spermine, and GABA with structural elements of brain cells. Neurochem Res 1976; 1:469-99. [DOI: 10.1007/bf00964210] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/1976] [Indexed: 11/25/2022]
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Kossorotow A, Wolf HU, Seiler N. Regulatory effects of polyamines on membrane-bound acetylcholinesterase. Biochem J 1974; 144:21-7. [PMID: 4462573 PMCID: PMC1168459 DOI: 10.1042/bj1440021] [Citation(s) in RCA: 46] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The effects of putrescene, spermidine and spermine on membrane-bound acetylcholinesterase from human erythrocyte ;ghosts' and the solubilized enzyme of the electric organ of the electric eel were studied by kinetic methods. Measurements were made by using a photometric method which made it possible to record the enzyme reaction in the steady-state phase. Substrate-concentration-dependent activation and inhibition of acetylcholinesterase by polyamines is similar to that by Na(+), K(+), Ca(2+), Mg(2+) and certain quaternary and bisquaternary amines. The kinetics suggest an allosteric reaction mechanism. On the basis of the kinetic results a role for the polyamines as modulators of synaptic acetylcholinesterase is proposed.
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