RESUMO
1 The aim of the present work was to examine the role of muscarinic acetylcholine receptors (mAChR) on DNA synthesis and CD40 expression in human fibroblast cells. Neonatal human skin fibroblast cultures were stimulated with carbachol in presence or absence of specific antagonists and the following parameters were measured: identification of mAChR subtypes, DNA synthesis, inositol phosphates (InsP) production and CD40 expression. 2 Human fibroblasts express mAChR with Kd 0.47 +/- 0.11 nm and Bmax 236 +/- 22 fmol mg protein(-1). Carbachol stimulates DNA synthesis, InsP and the expression of CD40. All these effects were inhibited by atropine, mustard hydrochloride (4-DAMP) and pirenzepine but not by AF-DX 116 and tropicamide, indicating that M3 and M1 mAChR are implicated in carbachol action. The relative Ki of the antagonists obtained by competition binding assay was in parallel to the relative potency for blocking both carbachol-stimulated InsP accumulation and DNA synthesis. 3 The intracellular pathway leading to carbachol-induced biological effects involved phospholipase C and calcium/calmodulin, as U-73122 and trifluoroperazine blocked carbachol effects, respectively. Calphostin C, a protein kinase C inhibitor, had no effect, indicating that this enzyme does not participate in the system. 4 These results may contribute to a better understanding of the modulatory role of the parasympathetic muscarinic system on normal human fibroblast function.
Assuntos
Antígenos CD40/biossíntese , DNA/biossíntese , Fibroblastos/efeitos dos fármacos , Agonistas Muscarínicos/farmacologia , Receptores Muscarínicos/efeitos dos fármacos , Atropina/farmacologia , Calmodulina/antagonistas & inibidores , Calmodulina/metabolismo , Carbacol/farmacologia , Células Cultivadas , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Estrenos/farmacologia , Fibroblastos/imunologia , Fibroblastos/metabolismo , Citometria de Fluxo , Humanos , Fosfatos de Inositol/metabolismo , Antagonistas Muscarínicos/farmacologia , Pirenzepina/farmacologia , Pirrolidinonas/farmacologia , Quinuclidinil Benzilato , Ensaio Radioligante , Receptor Muscarínico M1/análise , Receptor Muscarínico M1/efeitos dos fármacos , Receptor Muscarínico M1/metabolismo , Receptor Muscarínico M3/análise , Receptor Muscarínico M3/efeitos dos fármacos , Receptor Muscarínico M3/metabolismo , Receptores Muscarínicos/análise , Receptores Muscarínicos/metabolismo , Trifluoperazina/farmacologia , Fosfolipases Tipo C/antagonistas & inibidores , Fosfolipases Tipo C/metabolismoRESUMO
Taking into account that the activation of different subtypes of ileal muscarinic acetylcholine receptors (mAChR) regulate gut functions such as tone, motility, and electrolyte secretion, we characterized the expression of mAChR in ileal-purified membranes. We also studied intracellular signals triggered by mAChR activation. Binding parameters obtained from saturation assays with the nonselective tritiated muscarinic antagonist, quinuclidynil benzilate ([3H]-QNB), were maximal number of binding sites (Bmax): 30 +/- 2 fmol/mg prot and dissociation constant (Kd): 0.2 +/- 0.03 nM. The competitive inhibition of [3H]-QNB specific binding by various nonlabelled muscarinic antagonists was measured and the rank order of potency was: atropine (ATROP) > 4-DAMP > AF-DX 116 > pirenzepine (PZ). The activation of mAChR by carbachol (CARB) increased ileal motility in a concentration-dependent manner (EC50 2 x 10[-7] M). The antagonists' order of potency to displace dose-response curve of CARB was: ATROP > 4-DAMP > AF-DX116 > PZ. Optimal concentration of CARB on ileal strips increased phosphoinositide turnover and cGMP levels by activating ml receptor subtype and decreased isoproterenol (ISO) stimulated levels of cAMP due to M2 receptor activation. We can conclude that the activation of different mAchR subtypes triggers different intracellular signals that could regulate intestinal tone and motility.
Assuntos
Íleo/metabolismo , Receptores Muscarínicos/metabolismo , Transdução de Sinais , Animais , Membrana Celular/metabolismo , AMP Cíclico , GMP Cíclico , Ativação Enzimática , Íleo/citologia , Técnicas In Vitro , Fosfatos de Inositol , Cinética , Antagonistas Muscarínicos/farmacologia , Quinuclidinil Benzilato/farmacologia , Ratos , Receptores Muscarínicos/biossíntese , Análise de Regressão , Transdução de Sinais/fisiologiaRESUMO
We have previously shown that myocardium from experimental autoimmune myocarditis expresses H1 receptors not present in normal mice heart. ThEA acting via H1 receptors, augments cyclic AMP production in atria from autoimmune myocarditis mice without any effect on atria from control mice. Addition of mepyramine before ThEA caused cyclic AMP levels to fall to a level similar to basal, confirming the H1 receptor participation. Histamine at low concentrations mimicked the ThEA action on H1 receptor-stimulation of cyclic AMP production by autoimmune myocardium. The fact that the inhibition of phospholipase C blocked the cyclic AMP stimulation by ThEA, supports the assumption that this action is secondary to receptor-mediated hydrolysis of phosphoinositides, generating some oxidative metabolites (IP3-DAG), which in turn may be responsible for the cyclic AMP effect. So, the inhibition of protein kinase C and calcium/calmodulin partially prevented the stimulatory action of ThEA on cyclic AMP levels in autoimmune myocardium, suggesting that both pathways are implicated in this effect. Data shows that the stimulation of H1 receptors by specific agonist in atria from autoimmune myocarditis mice, augments the cyclic AMP, requiring the hydrolysis of phosphoinositide cycle. The role of this cyclic AMP augmentation in myocardium from autoimmune myocarditis mice, will provide a basis to assess the role of this second messenger as an important factor in the regulation and/or modulation of the physiological behaviour of the heart in the course of autoimmune myocarditis.
Assuntos
Doenças Autoimunes/metabolismo , AMP Cíclico/biossíntese , Miocardite/metabolismo , Receptores Histamínicos H1/fisiologia , Transdução de Sinais/efeitos dos fármacos , Animais , Cimetidina/farmacologia , AMP Cíclico/fisiologia , Átrios do Coração/metabolismo , Histamina/farmacologia , Agonistas dos Receptores Histamínicos/farmacologia , Antagonistas dos Receptores Histamínicos/farmacologia , Masculino , Camundongos , Fosfatidilinositóis/metabolismo , Pirilamina/farmacologia , Receptores Histamínicos H1/efeitos dos fármacos , Tiazóis/farmacologiaRESUMO
1. The aim of this paper was to determine the different signalling cascades involved in contraction of the rat urinary bladder detrusor muscle mediated via muscarinic acetylcholine receptors (muscarinic AChR). Contractile responses, phosphoinositides (IPs) accumulation, nitric oxide synthase (NOS) activity and cyclic GMP (cGMP) production were measured to determine the reactions associated with the effect of cholinergic agonist carbachol. The specific muscarinic AChR subtype antagonists and different inhibitors of the enzymatic pathways involved in muscarinic receptor-dependent activation of NOS and cGMP were tested. 2. Carbachol stimulation of M(3) and M(4) muscarinic AChR increased contractility, IPs accumulation, NOS activity and cGMP production. All of these effects were selectively blunted by 4-DAMP and tropicamide, M(3) and M(4) antagonists respectively. 3. The inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), neuronal NOS (nNOS) and soluble guanylate cyclase, but not of protein kinase C and endothelial NOS (eNOS), inhibited the carbachol action on detrusor contractility. These inhibitors also attenuated the muscarinic receptor-dependent increase in cGMP and activation of NOS. 4. In addition, sodium nitroprusside and 8-bromo-cGMP, induced negative relaxant effect. 5. The results obtained suggest that carbachol activation of M(3) and M(4) muscarinic AChRs, exerts a contractile effect on rat detrusor that is accompanied by an increased production of cGMP and nNOS activity. The mechanism appears to occur secondarily to stimulation of IPs turnover via PLC activation. This in turn, triggers cascade reactions involving CaM, leading to activation of nNOS and soluble guanylate cyclase. They, in turn, exert a modulator inhibitory cGMP-mediated mechanism limiting the effect of muscarinic AChR stimulation of the bladder.
Assuntos
Óxido Nítrico Sintase Tipo I/metabolismo , Receptor Muscarínico M3/fisiologia , Receptor Muscarínico M4/fisiologia , Bexiga Urinária/enzimologia , Animais , Carbacol/farmacologia , Agonistas Colinérgicos/farmacologia , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Técnicas In Vitro , Fosfatos de Inositol/metabolismo , Masculino , Antagonistas Muscarínicos/farmacologia , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculo Liso/efeitos dos fármacos , Músculo Liso/enzimologia , Músculo Liso/fisiologia , Piperidinas/farmacologia , Quinuclidinil Benzilato/farmacologia , Ratos , Ratos Wistar , Receptor Muscarínico M3/agonistas , Receptor Muscarínico M3/antagonistas & inibidores , Receptor Muscarínico M4/agonistas , Receptor Muscarínico M4/antagonistas & inibidores , Trítio , Tropicamida/farmacologia , Bexiga Urinária/metabolismo , Bexiga Urinária/fisiologiaRESUMO
Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that has a large number of immunologic and nonimmunologic functions. We have described that IFN-gamma could activate muscarinic cholinergic receptors (mAchR) of rat intestine, stimulating ileal motility. We also observed that mAchR activation induced inhibition of cAMP levels and stimulation of cGMP formation. The objectives of our work were to clarify the signal transduction pathways involved in regulation of ileal motility through mAchR activation by IFN-gamma. Our results demonstrate that this cytokine produces an ileal cholinergic response through tyrosine kinase activity. The activation of tyrosine kinase mediates ileal contractility, phosphoinositide hydrolysis by phospholipase C, nitric oxide synthase via protein kinase C, and cGMP synthesis. The increment in ileal motility is probably due to hyperproduction of prostaglandin E2 (PGE2) by ileal tissue. This prostanoid is an important mediator because it stimulates ileal motility. We conclude that IFN-gamma not only immunomodulates the gut microenvironment but also exerts a local nonimmunologic regulation on intestinal motility.
Assuntos
Íleo/efeitos dos fármacos , Interferon gama/farmacologia , Agonistas Muscarínicos/farmacologia , Proteínas Tirosina Quinases/metabolismo , Animais , GMP Cíclico/metabolismo , Ativação Enzimática , Motilidade Gastrointestinal/efeitos dos fármacos , Hidrólise , Íleo/enzimologia , Fosfatos de Inositol/metabolismo , Masculino , Óxido Nítrico Sintase/efeitos dos fármacos , Proteína Quinase C/efeitos dos fármacos , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Estimulação QuímicaRESUMO
Plasma membrane vesicles of Trypanosoma cruzi (PMVs) formed saturation binding isotherms with naive murine T lymphocytes. Parasite membrane attachment to the muscarinic cholinergic receptors of Lyt 2.2+T cells (suppressor cells) resulted in the synthesis of cGMP, attenuation of cAMP levels and in the secretion of prostaglandin E2, an immunoregulator effector substance. These T suppressor cell signals were blunted by atropine and by monospecific antibody against T. cruzi surface epitopes. The interaction of T. cruzi PMVs with the beta adrenergic receptors of Lyt L3T4+T cells (helper cells) resulted in the synthesis of cAMP and in the attenuation of cGMP levels. T helper cells did not secrete prostaglandin E2 when T. cruzi PMVs were added to this system. These T helper cell signals were blunted by propranolol and by monospecific antibody against T. cruzi surface epitopes. The interaction of T. cruzi with T lymphocytes may result, therefore, in the down-regulation of the immune response induced by prostaglandin E2 T suppressor cell secretion and by cAMP inhibition of proliferation of T helper cells.
Assuntos
Linfócitos B/parasitologia , Adesão Celular , Receptores Adrenérgicos beta/fisiologia , Receptores Muscarínicos/fisiologia , Transdução de Sinais , Linfócitos T/parasitologia , Trypanosoma cruzi/fisiologia , Animais , Linfócitos B/imunologia , Membrana Celular/parasitologia , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Dinoprostona/metabolismo , Coelhos , Transdução de Sinais/imunologia , Linfócitos T Citotóxicos/metabolismo , Linfócitos T Citotóxicos/parasitologia , Linfócitos T Auxiliares-Indutores/parasitologia , Linfócitos T Reguladores/metabolismo , Linfócitos T Reguladores/parasitologiaRESUMO
The presence of alpha-adrenergic receptors (absent in normal lymphocytes) has been demonstrated in transformed human lymphocytes of the Raji cell line. Binding properties of beta-adrenergic receptors were similar to those reported for normal lymphocytes. A single population of alpha 2-adrenergic receptors was characterized in intact Raji lymphoblasts by binding and saturation assays with the alpha 2-adrenergic antagonist yohimbine. Competition curves with [3H]yohimbine indicate the presence of typical alpha 2-adrenoceptors. Reaction of Raji with the alpha 2-adrenergic agonist clonidine (10(-6) M) stimulated their growth rate. In contrast, the alpha 1-adrenergic agonist methoxamine (10(-6) M) had no effect. Previous work indicates that Raji can actively produce thromboxanes (TX) and that these decreased atrium contractility. In agreement with these results and with the binding studies, it is now shown that clonidine stimulation enhanced the negative inotropic effects of Raji on isolated rat atria. This reaction was prevented by incubation of Raji with yohimbine (10(-6) M) but not with the alpha 1-adrenergic antagonist prazosin (10(-6) M) or the beta-adrenergic antagonist propranolol (10(-7) M). The biologic effect of Raji on rat atria was probably due to production of cyclooxygenase metabolites of arachidonic acid, because it was blocked by preincubation of the cells with the cyclooxygenase inhibitors indomethacin (10(-6) M) and aspirin (10(-4) M) or the thromboxane synthetase inhibitors nictindol (10(-5) M) and imidazole (10(-4) M).(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Transformação Celular Neoplásica/metabolismo , Linfócitos/química , Receptores Adrenérgicos alfa/análise , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Divisão Celular , Linhagem Celular , Clonidina/farmacologia , Humanos , Técnicas In Vitro , Indometacina/farmacologia , Masculino , Contração Miocárdica , Ratos , Ratos EndogâmicosRESUMO
Normal human lymphocytes (L) (8 X 10(5) ml-1) incubated with methoxamine (Me) (1 X 10(-7) M) (Me-L) triggered the mechanical response of the isolated vas deferens of the rat. L or Me alone did not modify this contractile activity at the concentrations cited above. Me alone (10(-6) to 10(-3) M) increased the tension of the vas. In the presence of L (8 X 10(5) ml-1) the dose-response curve to Me shifted to the left and the efficacy of Me was enhanced. Inhibitors of alpha 1-adrenoceptors completely blocked the reaction between Me and L while drugs that block alpha 1 and alpha 2-adrenoceptors reduced the reaction between Me-L and the vas deferens. Direct contact of Me-L with the assay organ was not necessary. Cell-free supernatants of L exposed to Me (Me-L supernatants) elicited the reaction in the same way as Me-L. This effect required the continuous presence of Me since dialyzed Me-L supernatants were inactive. Inhibitors of lipoxygenase(s) completely blocked the positive inotropic effect of Me-L or of Me-L supernatants. Inhibitors of cyclo-oxygenase potentiated this effect. These results suggest that Me reacts with alpha 1-adrenoceptors of L. From this reaction, soluble factors are released that potentiate the alpha-adrenoceptor stimulatory effect of Me on the vas deferens as a consequence of the release of oxidative products of the lipoxygenase/s pathway of arachidonic acid.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Ácidos Araquidônicos/sangue , Linfócitos/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Ácido Araquidônico , Ácidos Araquidônicos/fisiologia , Humanos , Técnicas In Vitro , Inibidores de Lipoxigenase , Linfócitos/metabolismo , Masculino , Metoxamina/farmacologia , Contração Muscular/efeitos dos fármacos , Ratos , Fatores de Tempo , Ducto Deferente/efeitos dos fármacosRESUMO
Normal human lymphocytes (4 X 10(5) ml-1) incubated with sodium arachidonate (8 X 10(-7)M) (NaA-L) induced a strong enhancement of the tension and frequency of spontaneously beating rat atria. Normal human lymphocytes (L) or NaA alone at 8 X 10(-7)M did not modify this contractile activity. Between 2 X 10(-6)M to 1 X 10(-5)M NaA alone increased the tension of the atria without effect on the rate. In the presence of L (4 X 10(5) ml-1) the dose-response curve to NaA shifted to the left, the potency and the efficiency of NaA were enhanced and the chronotropic action was triggered. Inhibitors of cyclo-oxygenase (indomethacin 1 X 10(-6)M or acetylsalicylic acid (ASA) 1.8 X 10(-4)M) completely blocked the positive inotropic effect induced by NaA alone. Inhibitors of lipoxygenase/s (nordihydroguaiaretic acid (NDGA) 1 X 10(-5)M or 5,8,11,14-eicosatetraynoic acid (ETYA) 1 X 10(-7)M did not modify this effect. Indomethacin and ASA did not block the positive inotropic and chronotropic effects of the lower concentration of NaA-L and significantly reduced the inotropic effect of the higher ones. NDGA and ETYA shifted to the right the inotropic and chronotropic dose-response curve to NaA-L. FPL-55712 (1 X 10(-7)M), the slow reacting substance of anaphylaxis (SRS-A) antagonist, significantly reduced the overall inotropic and chronotropic effect of NaA-L. Direct contact of NaA-L with the atria was not necessary. Cell-free supernatants of L exposed to NaA increased the tension and the frequency of beating rat atria. 7 The stimulatory effect of NaA-L supernatants did not occur if rat atria had been previously incubated with NDGA 1 x 10-5 M. On the other hand, the generation of stimulatory products from NaA-L was not prevented by preincubating L with 1 x 10-5 M NDGA. Hence SRS-A and/or other oxidative metabolites of arachidonic acid were produced by the atria. 8 These results suggest that NaA-L react in vitro with spontaneous beating rat atria, inducing inotropic and chronotropic effects. Moreover, the stimulatory action of NaA itself was potentiated by L. These reactions involved a balance between cyclo-oxygenase and lipoxygenase oxidative products with a central role for SRS-A.
Assuntos
Ácidos Araquidônicos/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Linfócitos/fisiologia , Contração Miocárdica/efeitos dos fármacos , Animais , Ácido Araquidônico , Aspirina/farmacologia , Técnicas In Vitro , Indometacina/farmacologia , Masculino , Ratos , Ratos Endogâmicos , Fatores de TempoRESUMO
The purpose of this study was to explore the pharmacological and biochemical mechanisms involved in diabetic cardiomyopathy, with particular interest in the abnormal function of cholinergic neurotransmission at the onset of the pathology. The muscarinic acethylcholine agonist carbachol showed a negative inotropic response on both normal and diabetic isolated atria, but the latter showed a supersensitive response. No changes were found in muscarinic acethylcholine receptor (mAChR) expression. Measurements of mAChR-associated second messengers indicated no significant differences between normal and diabetic rat atria in the stimulatory effect of carbachol on protein kinase C activity and the production of inositol phosphates, or in the inhibitory effect induced by carbachol on cyclic AMP (cAMP) production. On the contrary, nitric oxide (NO) synthase activity and cyclic GMP production were higher in diabetic cardiac preparations than in normal ones. Moreover, in diabetic atria, nitric oxide synthase and guanylate cyclase inhibitors shifted the carbachol concentration-response curve on contractility to the right, reaching values similar to those of normal atria. These results suggest an early alteration in the mACh system during the diabetic state, associated with increased production of nitric oxide and cyclic GMP (cGMP). This, in turn, could increase the biological mechanical activity of the mAChR agonist, inducing in this way a higher pharmacological response, without changes in mAChR expression.
Assuntos
Carbacol/farmacologia , Cardiomiopatias/metabolismo , GMP Cíclico/metabolismo , Diabetes Mellitus Experimental/metabolismo , Agonistas Muscarínicos/farmacologia , Óxido Nítrico Sintase/metabolismo , Receptores Muscarínicos/metabolismo , Sistemas do Segundo Mensageiro , Animais , Cardiomiopatias/enzimologia , Cardiomiopatias/etiologia , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/enzimologia , Relação Dose-Resposta a Droga , Técnicas In Vitro , Masculino , Óxido Nítrico Sintase/efeitos dos fármacos , Ratos , Ratos Wistar , Receptores Muscarínicos/efeitos dos fármacosRESUMO
In this study, we investigated the expression and distribution of muscarinic cholinergic receptors (mAChRs) and the different signaling pathways associated with mAChR activation in atria isolated from adult and neonatal rats. Carbachol stimulation of mAChRs in both neonatal and adult rat atria led to a negative inotropic response with activation of phosphoinositide hydrolysis, an increase in cyclic GMP levels, and a decrease in cyclic AMP production. However, compared with adult atria, neonatal atria showed hypersensitivity in the contractile effect induced by carbachol. Pharmacological analysis with mAChR antagonists indicated that M1 and M2 mAChR subtypes are important mediators of the response to carbachol in neonatal atria. In contrast, in adult atria the effect of the agonist was coupled only to the M2 mAChR subtype. Moreover, an increased number of total mAChRs was labeled in neonatal atrial membranes compared with those of adults. Although a predominant M2 mAChR population is expressed in atria at both stages of development studied, competition binding parameters calculated for carbachol indicated the presence of high-affinity binding sites, with higher affinity in neonates than in adults. These results suggest that the differences observed between neonatal and adult atria in their response to a cholinergic agonist may be related to differential expression of mAChR subtypes and/or changes in functional coupling of mAChR subtypes during development.
Assuntos
Coração/efeitos dos fármacos , Agonistas Muscarínicos/farmacologia , Contração Miocárdica/fisiologia , Receptores Muscarínicos/fisiologia , Transdução de Sinais/fisiologia , Fatores Etários , Animais , Animais Recém-Nascidos , Carbacol/farmacologia , Átrios do Coração/efeitos dos fármacos , Fosfatos de Inositol/metabolismo , Contração Miocárdica/efeitos dos fármacos , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Wistar , Receptor Muscarínico M1 , Receptor Muscarínico M2RESUMO
The inotropic effect of isoproterenol, as well as the beta-adrenoceptor population, was measured in pregnant uterine tissue from female spontaneous hypertensive rats (SHR) (control group: C) and female SHR that were grafted with skin from Holtzman male rats (eclamptic group: E). The Kd value of the concentration-response curve of isoproterenol was higher for uteri from E rats than C rats. This phenomenon was not accompanied by a modification in the expression of beta-adrenoceptors. Inhibition of the synthesis of prostaglandins prevented the hyporeactivity to isoproterenol during eclampsia. Moreover, uteri from E rats generated and released greater amounts of prostaglandin E2 (PGE2) than uteri from C rats, even in the presence or absence of isoproterenol. In addition, whereas isoproterenol administered alone increased basal cyclic AMP (cAMP) production from C uteri, PGE2 administered alone enhanced cAMP production in E uterine tissue. These results suggest that the decrease in beta-adrenergic response to the agonist in E rats is ascribed to PGE2 production. The abnormal reactivity to the beta-agonist could be associated with a heterologous desensitization of uterine beta-adrenoceptors exerted by PGE2 overload in uteri from E rats. These results bear directly on the regulation of uterine motility during pregnancy, since an impaired response to beta-adrenergic innervation could lead to increased uterine motility, impairing the maintenance of pregnancy.
Assuntos
Dinoprostona/farmacologia , Eclampsia/metabolismo , Receptores Adrenérgicos beta/efeitos dos fármacos , Útero/metabolismo , Agonistas alfa-Adrenérgicos/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Animais , AMP Cíclico/metabolismo , Dinoprostona/metabolismo , Relação Dose-Resposta a Droga , Feminino , Técnicas In Vitro , Isoproterenol/farmacologia , Masculino , Metoxamina/farmacologia , Gravidez , Ratos , Ratos Endogâmicos SHR , Receptores Adrenérgicos beta/metabolismo , Contração Uterina/efeitos dos fármacos , Útero/efeitos dos fármacosRESUMO
The rat isolated vas deferens produces and releases prostanoids into an incubation medium. Production of these substances from the exogenous precursor 14C arachidonic acid was studied in prepubertal, pubertal and adult animals. Synthesis of prostaglandin F, prostaglandin E, prostaglandin D and thromboxane B2 is lower in prepubertals arid increases significantly in pubertals, with no further modifications in adults. Castration of pubertals and adults dramatically reduces the production of all measured arachidonic acid metabolites but does not modify it in prepubertals. Replacement therapy with testosterone propionate significantly enhances prostanoid production in pubertal and adult castrated rats. Similar treatment on normal prepubertals also increases synthesis, indicating that androgens could be modulators of prostanoid synthesis in vas deferens. The lower effects obtained treating castrated adults with progesterone and with 17-beta estradiol suggest an action, at least partially specific for androgenic steroids. It is concluded that prostanoid production by the rat vas deferens from an exogenous precursor is closely related to the presence of androgens.
Assuntos
Prostaglandinas/biossíntese , Testosterona/farmacologia , Ducto Deferente/efeitos dos fármacos , Fatores Etários , Animais , Ácido Araquidônico/metabolismo , Radioisótopos de Carbono , Cromatografia em Camada Fina , Masculino , Ratos , Ratos Wistar , Ducto Deferente/metabolismoRESUMO
The biological properties of Thromboxane B2 (TXB2) on isolated rat heart were studied. Its actions were compared with U-46619 a Thromboxane A2 mimetic compound and with isoproterenol. TXB2 induced a concentration-dependent increase in contractility, that was non-competitively antagonized by propranolol. In addition TXB2 inhibited Na+ + K+-ATPase activity at the same concentrations that influenced the mechanical activity. Inhibition of beta-adrenoceptors efficiently blocked the inhibitory action of TXB2 upon Na+ + K+-ATPase-activity. Isoproterenol simulated the positive inotropic effect and the inhibitory action of TXB2 on Na+ + K+-ATPase-activity. In contrast, U-46619 did not alter the basal dF/dt, neither the enzyme activity. The foregoing results suggest that TXB2 resembles the biological effect of catecholamines-inducing stimulation of myocardial contractility and inhibition of Na+ + K+-ATPase activity.
Assuntos
Contração Miocárdica/efeitos dos fármacos , Receptores Adrenérgicos beta/efeitos dos fármacos , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Tromboxano B2/farmacologia , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico , Animais , Relação Dose-Resposta a Droga , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Isoproterenol/farmacologia , Endoperóxidos Sintéticos de Prostaglandinas/farmacologia , RatosRESUMO
We have examined the influence of an allogeneic stimulus on T lymphocyte prostanoid synthesis. PGE2 and TXB2 (the stable product of TXA2) were determined by radioimmunoassay. When T cells were derived from alloimmunized animals, the production of PGE2 and TXA2 was significantly higher than that of non-immunized cells. Moreover, T immune lymphocytes in the presence of the immunized alloantigen showed an increment in prostanoid production. We propose that the allogeneic stimulus provides a signal to the T lymphocytes for an increase in prostanoid synthesis.
Assuntos
Prostaglandinas/biossíntese , Linfócitos T/metabolismo , Tromboxanos/biossíntese , Animais , Dinoprostona/biossíntese , Feminino , Imunização , Técnicas In Vitro , Linfócitos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos AKR , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Tromboxano B2/biossínteseRESUMO
Prostaglandin E2 (PGE2) and cAMP production in allogeneic and syngeneic pregnant mice uteri, were measured in relation to the ratio of plasma estrogen/progesterone levels. PGE2 generation by allopregnant uteri varied with the days of pregnancy. The increment of the prostanoid coincided with the increase in plasma estrogen concentration, whereas the decrement of its production was in parallel with the increment of plasma progesterone. The syngeneic pregnant uterus was unable to increase the release of PGE2 above basal values during the whole pregnancy. The rise of PGE2 production by the allogeneic pregnant uterus was correlated with an increase in cAMP levels. It is proposed that the pregnant mouse uterus increases its ability to release PGE2 in response to an ovarian steroids.
Assuntos
AMP Cíclico/biossíntese , Dinoprostona/biossíntese , Útero/metabolismo , Animais , Cruzamentos Genéticos , Dinoprostona/genética , Estrogênios/sangue , Feminino , Idade Gestacional , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Gravidez , Progesterona/sangue , Especificidade da Espécie , Útero/fisiologiaRESUMO
The mechanisms by which beta adrenergic stimulation regulates phagocytosis of Candida albicans by human peripheral monocytes (HPM) are characterized. Isoproterenol (ISO) inhibits phagocytosis in a concentration-dependent manner. This effect was blunted by propranolol, inhibitors of phospholipase A2 (PLA2), cyclooxygenase and verapamil, pointing to a participation of arachidonic acid (AA) metabolites and calcium in the phenomenon. Prostaglandin E2 (PGE2) and dibutyryl cyclic AMP (db-cAMP) also exerted the same inhibitory effect on phagocytosis. ISO interacts with beta adrenergic receptors of HPM increasing PGE2 and cAMP. We conclude that the mechanisms by which beta adrenergic stimulation regulates phagocytosis of Candida albicans by HPM appear to be secondary to beta adrenoceptor-mediated hydrolysis of AA accompanied by an increase in PGE2 generation and cAMP production. Both PGE2 and cAMP could act as mediators of the inhibitory action of beta agonists on the HPM-phagocytosis process.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Ácido Araquidônico/fisiologia , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Fagocitose/efeitos dos fármacos , Acetofenonas/administração & dosagem , Acetofenonas/farmacologia , Agonistas Adrenérgicos beta/administração & dosagem , Antagonistas Adrenérgicos beta/administração & dosagem , Antagonistas Adrenérgicos beta/farmacologia , Ácido Araquidônico/metabolismo , Ácido Araquidônico/farmacologia , Bucladesina/administração & dosagem , Bucladesina/farmacologia , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/administração & dosagem , Bloqueadores dos Canais de Cálcio/farmacologia , Candida albicans/efeitos dos fármacos , Candida albicans/imunologia , Candida albicans/metabolismo , AMP Cíclico/metabolismo , Inibidores de Ciclo-Oxigenase/farmacologia , Dinoprostona/administração & dosagem , Dinoprostona/metabolismo , Dinoprostona/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacologia , Humanos , Indometacina/administração & dosagem , Indometacina/farmacologia , Isoproterenol/administração & dosagem , Isoproterenol/farmacologia , Ocitócicos/administração & dosagem , Ocitócicos/farmacologia , Fosfolipases A/antagonistas & inibidores , Fosfolipases A2 , Propranolol , Prostaglandina-Endoperóxido Sintases/efeitos dos fármacos , Receptores Adrenérgicos beta/efeitos dos fármacos , Receptores Adrenérgicos beta/metabolismo , Verapamil/administração & dosagem , Verapamil/farmacologiaRESUMO
59Fe was incorporated in vivo into intestinal sacs prepared in iron deficient rats and 59Fe counts were detected in blood, spleen, liver, femur and intestine. The i.v. injection of isoproterenol (i.v. 2 micrograms/rat) or N',O'-dibutyryladenosine 3',5'-cyclic monophosphate (10 microM/100 g b.w.) enhanced significantly the iron counts in blood, spleen, liver and femur but not in intestine. (-)-Propranolol (2 mg X kg-1 b.w. i.v.) antagonized the stimulatory effect of isoproterenol. It is suggested that isoproterenol increases iron absorption via the stimulation of beta-adrenoreceptors of the intestinal mucosa.
Assuntos
Absorção Intestinal , Ferro/metabolismo , Receptores Adrenérgicos beta/fisiologia , Animais , Bucladesina/farmacologia , Radioisótopos de Ferro , Isoproterenol/farmacologia , Masculino , Propranolol/farmacologia , Ratos , Ratos Endogâmicos , Distribuição TecidualRESUMO
Contractile responses to exogenous sodium arachidonate (NaA) were studied in auricles from normal and acutely diabetic (streptozotocin-treated) rats. NaA induced a concentration-dependent positive inotropic effect in atria from normal and diabetic rats but the magnitude of the contractile influence of the fatty acid was different in both types of auricles, i.e. diabetic atria had a greater responsiveness to NaA than normal preparations. Blockers of arachidonic acid (AA) metabolism via cyclo-oxygenase (indomethacin and acetylsalicylic acid), abolished the stimulatory influence of NaA in normal and in diabetic auricles. Moreover, incubation with tranylcipromine, a prostacyclin synthetase inhibitor, reduced the inotropic effect of NaA in normal atria, but failed to modify it in the diabetic atria. On the other hand, inhibitors of thromboxane (TX) synthetase (imidazole and L-8027) diminished the effect of NaA in diabetic preparations without altering the contractile responses in the controls. In the presence of lipoxygenase blocking agents (nordihydroguaiaretic acid and dithizone), the influence of NaA was reduced at normal values only in the atria from diabetic rats. Both atrial preparations (normal and diabetic) converted ([1-14C]arachidonic acid (AA) into PGI2 (assessed as 6-oxo-PGF1 alpha) and TXB2. Moreover, normal atria generated more PGI2 than TXB2 whereas TXB2 production was greater than that of PGI2 in diabetic atria. The foregoing results suggest that in non-diabetic atria the effect of exogenous NaA may be attributed to metabolites generated by the sequential action of cyclo-oxygenase and prostacyclin synthetase. On the other hand, the contractile action of exogenous NaA in diabetic atria may be ascribed to thromboxanes and lipoxygenase(s) metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ácidos Araquidônicos/farmacologia , Diabetes Mellitus Experimental/fisiopatologia , Contração Miocárdica/efeitos dos fármacos , Animais , Ácido Araquidônico , Ácidos Araquidônicos/metabolismo , Radioisótopos de Carbono , Inibidores de Ciclo-Oxigenase , Epoprostenol/antagonistas & inibidores , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Inibidores de Lipoxigenase , Masculino , Ratos , Ratos Endogâmicos , Estimulação Química , Tromboxano-A Sintase/antagonistas & inibidoresRESUMO
The effects of IgG purified from BALB/c anti CF1 sera on the spontaneous contractions of isolated oviductal tract from CF1 mice were explored. Cumulative dose-response curves were constructed for the effect of immune IgG on nice oviductal tracts from proestrus, estrus, metestrus and diestrus, comparing them with those obtained with norepinephrine. Both the adrenergic agonist and the immune IgG produced a sustained inhibition of spontaneous motility during the whole sex cycle. Normal IgG was virtually devoid of activity. The sensitivity of CF1 mouse oviducts to the inhibitory actions of immune IgG and norepinephrine varied depending on the hormonal stage, i.e. it was higher in natural diestrus than in metestrus; it became smaller in proestrus and was minimal during estrus. The mechanism triggered involved a beta-adrenergic reaction that could be blocked by 10(-7) M (-)-propranolol and 10(-6) M butoxamine and potentiated by chemical sympathectomy of the mice with 6-hydroxydopamine. It is concluded that: (a) alloimmune antibody reacts with isolated oviductal tract of mice inducing functional changes; (b) this action could be associated with an activation of postsynaptic beta-adrenergic sites of the plasma membrane and (c) the different effectiveness of the immune IgG observed during the sex cycle appears to depend on the affinity of beta-adrenoreceptors to react with it.