RESUMO
The application of molecular cloning has revealed the phenomenal diversity and complexity of the phosphodiesterase isoenzyme family. Thus, more than 30 human phosphodiesterases are now known; all are apparently necessary for the seemingly simple task of hydrolysing the 3'-ester bond of either cyclic adenosine monophosphate or cyclic guanosine monophosphate. The availability of phosphodiesterase isoenzymes as pure recombinant proteins has greatly facilitated the identification of potent, selective inhibitors. The potential of these inhibitors to therapeutically exploit the molecular diversity of the phosphodiesterases has progressed significantly. A number of drugs are in clinical trials for asthma, and Viagra has become the first selective phosphodiesterase inhibitor to be approved by the US Food and Drug Administration.
Assuntos
Inibidores de Fosfodiesterase/uso terapêutico , Diester Fosfórico Hidrolases/metabolismo , Ensaios Clínicos como Assunto , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Inibidores de Fosfodiesterase/química , Diester Fosfórico Hidrolases/química , Diester Fosfórico Hidrolases/genéticaRESUMO
PURPOSE: To test if recombinant tissue inhibitor of metalloproteinases (TIMP-1) was effective in reducing corneal ulceration after alkali injury to the rabbit cornea. The effect of TIMP-1 was compared with that of a proven synthetic metalloproteinase inhibitor. METHODS: After a defined alkali injury to the rabbit cornea, a topical treatment regimen was followed for 24 days; one group was treated with vehicle only, a second group with recombinant TIMP-1, and a third group with the synthetic metalloproteinase inhibitor. Corneas were scored for ulceration during the 24-day period and the scores for the three groups were compared. RESULTS: The incidence and progression of ulceration and perforation, in the alkali-burned corneas receiving treatment with recombinant TIMP-1 or the synthetic inhibitor, were significantly less than in corneas receiving vehicle treatment alone. CONCLUSION: Recombinant TIMP-1 is as effective as a proven synthetic inhibitor in ameliorating corneal ulceration and perforation after an alkali injury.
Assuntos
Queimaduras Químicas/tratamento farmacológico , Úlcera da Córnea/prevenção & controle , Queimaduras Oculares/induzido quimicamente , Glicoproteínas/farmacologia , Inibidores de Metaloproteinases de Matriz , Metaloendopeptidases/farmacologia , Proteínas Recombinantes/farmacologia , Administração Tópica , Animais , Queimaduras Químicas/complicações , Queimaduras Químicas/patologia , Córnea/efeitos dos fármacos , Úlcera da Córnea/etiologia , Úlcera da Córnea/patologia , Modelos Animais de Doenças , Queimaduras Oculares/complicações , Queimaduras Oculares/tratamento farmacológico , Queimaduras Oculares/patologia , Feminino , Glicoproteínas/administração & dosagem , Incidência , Masculino , Metaloendopeptidases/administração & dosagem , Coelhos , Distribuição Aleatória , Proteínas Recombinantes/administração & dosagem , Hidróxido de Sódio , Inibidores Teciduais de MetaloproteinasesRESUMO
1. Prostaglandin E1 is chemotactic at concentrations down to 10 ng/ml for rabbit polymorphonuclear (PMN) leucocytes. Prostaglandins E2 and F2alpha have little or no chemotactic effect at concentrations up to 10 mug/ml. 2. Washed PMN leucocytes produced a chemotactic agent during phagocytosis, but not in the presence of indomethacin (28 muM). 3. Phagocytosing PMN leucocytes produce up to ten times as much prostaglandin as do resting cells. Some of this is prostaglandin E1 as judged by thin layer chromatography and differential bioassay. This prostaglandin production by PMN leucocytes is abolished by indomethacin (28 muM). 4. Ultrasonicated suspensions of PMN leucocytes produced prostaglandin from arachidonic aicd. This synthesis is inhibited by indomethacin. 5. Homogenates of PMN leucocytes which have been pre-incubated withe bacteria for 30 min show more prostaglandin synthetase activity than homogenates from PMN leucocytes which have not been exposed to bacteria. 6. It is concluded that in some forms of inflammation, prostaglandin E1 may play a controlling role in cellular migration. 7. PMN leucocytes may contribute to the generation of prostaglandins found in some inflammatory lesions.
Assuntos
Quimiotaxia , Leucócitos/fisiologia , Fagocitose , Prostaglandinas/fisiologia , Animais , Bactérias , Técnicas In Vitro , Indometacina/farmacologia , Leucócitos/metabolismo , Prostaglandinas/biossíntese , Prostaglandinas E/fisiologia , Prostaglandinas F/fisiologia , Coelhos , SonicaçãoRESUMO
1 Isolated rings of hamster aorta produced an unstable substance which inhibited platelet aggregation in vitro and had the same characteristics as prostacyclin. 2 Prostacyclin inhibited adenosine diphosphate (ADP)-induced aggregation of hamster platelets in vitro. 3 The effects of prostacyclin on ADP-induced platelet thrombi in the microcirculation of the hamster cheek pouch were studied with a television microscope. 4 Prostacyclin caused a dose-dependent increase in the time of iontophoretic application of ADP which was required to induce platelet thrombi formation and embolization in venules (30 to 40 micron diameter). 5 Prostacyclin caused a dose-dependent reduction in the total time during which ADP-induced thrombi were observed following local electrical damage to arterioles (40 to 80 micron diameter). 6 Thrombus formation in venules and arterioles was abolished by 500 ng/ml prostacyclin in the Krebs solution superfusing the hamster cheek pouch. 7 Prostacyclin was approximately twenty times more potent than prostaglandin E1 in preventing thrombus formation in the microcirculation.
Assuntos
Epoprostenol/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Prostaglandinas/farmacologia , Animais , Arteríolas/efeitos dos fármacos , Velocidade do Fluxo Sanguíneo , Bochecha/irrigação sanguínea , Cricetinae , Técnicas In Vitro , Masculino , Mesocricetus , Fluxo Sanguíneo Regional/efeitos dos fármacos , Vênulas/efeitos dos fármacosRESUMO
1. Two selective inhibitors of arachidonate 5-lipoxygenase, BW A4C and BW A797C, have been studied for their effects on acute inflammatory responses following oral administration to rats and mice. 2. The concentrations of the lipoxygenase product leukotriene B4 (LTB4) in 6 h inflammatory exudates, induced in rats by the subcutaneous implantation of carrageenin-soaked polyester sponges, were reduced dose-dependently by BW A4C (ED50 = 2.6 mg kg-1) or BW A797C (ED50 = 14.3 mg kg-1). 3. BW A4C and BW A797C had little or no effect on prostaglandin E2 (PGE2) concentrations in inflammatory exudates (ED50s greater than 100 mg kg-1). 4. Doses of up to 200 mg kg-1 of either BW A4C or BW A797C had no effect on carrageenin-induced oedema in rat paws. 5. BW A4C and BW A797C had little or no effect on carrageenin-induced hyperalgesia in rats or phenyl-benzoquinone-induced writhing in mice. 6. Yeast-induced pyrexia in rats was reduced by both BW A4C (ED50 = 32 mg kg-1) and BW A797C (ED50 = 23 mg kg-1). 7. The accumulation of leucocytes in sponge exudates was reduced dose-dependently by BW A4C (ED50 = 54 mg kg-1) and BW A797C (ED50 = 16.7 mg kg-1). 8. The selective lipoxygenase inhibitors BW A4C and BW A797C do not suppress inflammatory oedema or pain although they are anti-pyretic and they do inhibit leucocyte migration. There is not, however, a close agreement between these in vivo activities and their potencies as lipoxygenase inhibitors.
Assuntos
Araquidonato Lipoxigenases/antagonistas & inibidores , Ácidos Hidroxâmicos/farmacologia , Inflamação/tratamento farmacológico , Inibidores de Lipoxigenase , Pirazóis/farmacologia , 4,5-Di-Hidro-1-(3-(Trifluormetil)Fenil)-1H-Pirazol-3-Amina , Doença Aguda , Animais , Dinoprostona , Feminino , Contagem de Leucócitos/efeitos dos fármacos , Leucotrieno B4/sangue , Masculino , Camundongos , Camundongos Endogâmicos , Prostaglandinas E/sangue , Ratos , Ratos EndogâmicosRESUMO
1. The relationship between phagocytic leucocyte infiltration and cartilage degradation in immune arthritis has been investigated in groups of normal and neutropenic rabbits. 2. Injection of antigen into the knee joints of sensitized control animals induced joint swelling, prostaglandin E2 (PGE2) synthesis, leucocyte accumulation and proteoglycan loss from articular cartilage. 3. Intravenous injection of nitrogen mustard caused a selective depletion of circulating neutrophils and monocytes with little or no effect on platelets or lymphocytes. In neutropenic animals challenged with antigen, there was virtually no joint swelling, PGE2 synthesis or leucocyte infiltration but cartilage proteoglycan loss was unchanged after 1 day and increased by day 4 compared to control animals. 4. The numbers of circulating leucocytes returned to normal 3-4 days after nitrogen mustard treatment and leucocyte infiltration occurred in antigen-challenged joints but this was not accompanied by joint swelling. Subsequent intra-articular injection of PGE2 did, however, cause swelling. 5. Lysosomal enzyme levels in arthritic joint fluids were measured. The levels of beta-glucuronidase, which is released by activated phagocytes, were decreased in neutropenic animals but the levels of N-acetyl-beta-glucosaminidase, which is a marker of tissue damage, were not changed by neutrophil depletion. 6. Intra-articular injections of the cytokine interleukin-1 (IL-1) induced a pattern of leucocyte infiltration and cartilage proteoglycan loss similar to that seen in immune arthritis. In neutropenic animals, IL-1 did not cause significant accumulation of leucocytes in the joint but the loss of proteoglycan from cartilage was unimpaired. 7. These results indicate that both leucocyte infiltration and prostaglandin synthesis are required for joint swelling but that tissue degradation is mediated by resident cells. It is likely that release of IL-1 by synovial cells stimulates the synthesis and activation of metalloproteinases which initiate the process of tissue degradation.
Assuntos
Artrite Experimental/metabolismo , Artrite/metabolismo , Cartilagem Articular/metabolismo , Leucócitos/fisiologia , Proteoglicanas/metabolismo , Animais , Artrite Experimental/fisiopatologia , Cartilagem Articular/efeitos dos fármacos , Dinoprostona/metabolismo , Exsudatos e Transudatos/metabolismo , Glicosaminoglicanos/metabolismo , Hidroxiprolina/metabolismo , Interleucina-1/farmacologia , Articulações/fisiopatologia , Lisossomos/enzimologia , Masculino , CoelhosRESUMO
The cytokine interleukin-1 beta (IL-1 beta) is a potent hyperalgesic agent in the rat whereas IL-1 alpha is relatively inactive (Ferreira et al., 1988). IL-1 beta induced a dose-dependent increase in the sensitivity of rat paws to mechanical stimulation following intra-plantar injection but this effect was not reduced by indomethacin (1.0 mg kg-1, p.o.), at a dose known to inhibit completely prostaglandin synthesis in the rat (Salmon et al., 1983). Prostaglandin (PG)E2 enhanced sensitivity to both mechanical pressure and increased temperature but IL-1 beta enhanced only sensitivity to pressure. These observations indicate that IL-1 beta sensitized pressure-sensitive but not temperature-sensitive sensory neurones, through a prostaglandin-independent mechanism. Hyperalgesia induced by IL-1 beta but not PGE2, was inhibited by the neuropeptide melanocyte-stimulating hormone (alpha MSH) and its analogue [Nle4, D-Phe7] alpha MSH which are known to antagonize IL-1 responses in other systems (Holdeman & Lipton, 1985; Cannon et al., 1986). IL-1 beta-induced hyperalgesia was also reduced by the putative IL-1 beta antagonist Lys-D-Pro-Thr (Ferreira et al., 1988) but alpha MSH and its analogue were 10-50 times more potent.
Assuntos
Interleucina-1/antagonistas & inibidores , Neuropeptídeos/farmacologia , Dor/induzido quimicamente , Prostaglandinas/fisiologia , Animais , Relação Dose-Resposta a Droga , Indometacina/farmacologia , Masculino , Hormônios Estimuladores de Melanócitos/farmacologia , Dor/fisiopatologia , Ratos , Ratos Endogâmicos , Tempo de Reação/efeitos dos fármacosRESUMO
1. The inflammatory effects of hydroperoxy (HPETE) and hydroxy (HETE) acids, synthesized by arachidonic acid lipoxygenases, have been investigated in rabbit skin. 2. High doses (10-20 micrograms) of 5-, 12- or 15-HPETE or the 5,12-di-hydroxy acid, leukotriene B4 (0.1-1 micrograms), caused small but significant increases in plasma exudation following intra-dermal injection. 3. Leukotriene B4 was equipotent with prostaglandin E2 and prostacyclin in potentiating bradykinin-induced plasma exudation, and was 100 times more active in this property than any other lipoxygenase product tested. 4. Leukotriene B4-induced plasma exudation was enhanced by prostaglandin E2. 5. The mono-HETEs were relatively inactive in causing or enhancing plasma exudation. 6. Leukotriene B4 (0.1 microgram) or prostaglandin E1 (1.0 micrograms) significantly elevated leukocyte accumulation in rabbit skin, whereas PGE2, 5-HPETE, 5-HETE, 12-HPETE or 12-HETE were inactive at doses up to 1 microgram.
Assuntos
Ácidos Araquidônicos/farmacologia , Inflamação/induzido quimicamente , Leucotrienos , Peróxidos Lipídicos , Pele/efeitos dos fármacos , Ácido 12-Hidroxi-5,8,10,14-Eicosatetraenoico , Animais , Bradicinina/farmacologia , Relação Dose-Resposta a Droga , Epoprostenol/farmacologia , Exsudatos e Transudatos/efeitos dos fármacos , Leucócitos/efeitos dos fármacos , Leucotrieno B4 , Prostaglandinas E/farmacologia , CoelhosRESUMO
Although cyclo-oxygenase products have been detected at inflammatory sites the tissue of origin remains uncertain. Inflammatory exudates were collected from rats 4, 6, 8, 12 or 24 h after subcutaneous implantation of carrageenin-impregnated sponges. Concentrations of the cyclo-oxygenase products prostaglandin E2 (PGE2), 6-oxo-PGF1 alpha and thromboxane B2 (TXB2) in inflammatory exudates and serum (obtained from blood clotted at 37 degrees C) were measured by specific radioimmunoassays. TXB2 concentrations in exudates increased to about 100 ng ml-1 at 8 h but decreased to less than 20 ng ml-1 after 24 h. PGE2 concentrations increased from 4-12 h and remained between 80 and 120 ng ml-1 from 12-24 h. 6-oxo-PGF1 alpha had the same time course as that of PGE2 but concentrations were approximately one third of PGE2 values. TXB2 concentrations in serum from thrombocytopaenic rats were less than 5% of control values. Thrombocytopaenia did not affect TXB2, PGE2 or 6-oxo-PGF1 alpha concentrations or total leukocyte numbers in inflammatory exudates. Methotrexate-induced neutropaenia did not affect serum TXB2 concentrations but cyclo-oxygenase products (including TXB2) in 6 h inflammatory exudates were reduced by 60-95%. Colchicine (1.0 mg kg-1 s.c.) prevented leukocyte accumulation in sponge exudates and this was accompanied by a reduction in TXB2, PGE2 and 6-oxo-PGF1 alpha concentrations at 6 h. These results indicate that platelets are the source of TXB2 in clotting blood but do not contribute to cyclo-oxygenase activity in experimental inflammation. The results also suggest that migrating leukocytes are the major source of thromboxane and to a lesser degree prostaglandins in acute 6 h inflammatory exudates.
Assuntos
Inflamação/metabolismo , Prostaglandinas/biossíntese , Tromboxanos/biossíntese , Animais , Plaquetas/metabolismo , Colchicina/farmacologia , Exsudatos e Transudatos/metabolismo , Contagem de Leucócitos , Masculino , Neutropenia/metabolismo , Radioimunoensaio , Ratos , Trombocitopenia/metabolismo , Tromboxano B2/metabolismoRESUMO
1. The effects of the inhaled corticosteroid budesonide and a novel PDE 4 inhibitor CDP840 given systematically, were evaluated in a model of antigen-induced airway inflammation in the rabbit. 2. Adult litter-matched NZW rabbits (2.4-3.5 kg) immunised within 24 h of birth with Alternaria tenuis antigen were pretreated with budesonide (total dose 100 micrograms, inhaled over 2 days) or CDP840 (total dose 7 mg kg-1, i.p. over 3 days), before antigen challenge. For each drug-treated group a parallel group of rabbits was pretreated with the appropriate vehicle. In all groups airway responsiveness to inhaled histamine was assessed and bronchoalveolar lavage (BAL) performed 24 h before and after antigen challenge. 3. Basal lung function in terms of total lung resistance (RL; cmH2O l 1s-1) and dynamic compliance (Cdyn; ml cmH2O-1) were unaltered by pretreatment with budesonide or CDP840 compared to their respective vehicles 24 h before or after antigen challenge. 4. The RL component of the acute bronchoconstriction induced by inhaled Alternaria tenuis aerosol was unaffected by pretreatment with budesonide. However, budesonide prevented the fall in Cdyn due to antigen. Treatment with CDP840 significantly reduced antigen-induced acute bronchoconstriction in terms of both RL and Cdyn. 5. Airway hyperresponsiveness (AHR) to inhaled histamine was indicated by reduced RL PC50 (2.4-4.5 fold) and Cdyn PC35 (2.1-3.9 fold) values 24 h after antigen challenge. Treatment with either budesonide or CDP840 abolished the antigen-induced increase in responsiveness to inhaled histamine. 6. Total cells recovered per ml of BAL fluid increased 24 h after antigen challenge. Antigen-induced pulmonary eosinophilia was reduced (93%) in budesonide and (85%) in CDP840 treated rabbits. Antigen-induced increases in neutrophil numbers were reduced (76%) with budesonide but not CDP840 pretreatment. 7. Inhalation of Alternaria tenuis aerosol elicited an acute bronchoconstriction, followed 24 hours later by an increased responsiveness to inhaled histamine and pulmonary neutrophil and eosinophil recruitment. CDP840 was more effective than budesonide in preventing the antigen-induced increase in total lung resistance (RL); however, both drugs prevented the antigen-induced reduction in dynamic compliance (Cdyn). CDP840 and budesonide also prevented antigen-induced AHR and eosinophilia in the immunised rabbit.
Assuntos
Anti-Inflamatórios/farmacologia , Antagonistas dos Receptores Histamínicos/farmacologia , Inibidores de Fosfodiesterase/farmacologia , Pregnenodionas/farmacologia , Piridinas/farmacologia , Administração por Inalação , Resistência das Vias Respiratórias/efeitos dos fármacos , Análise de Variância , Animais , Asma/tratamento farmacológico , Hiper-Reatividade Brônquica , Líquido da Lavagem Broncoalveolar , Broncoconstrição/efeitos dos fármacos , Budesonida , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Humanos , Técnicas In Vitro , Pulmão/efeitos dos fármacos , Pulmão/fisiopatologia , Masculino , Neutrófilos/efeitos dos fármacos , Coelhos , Hipersensibilidade Respiratória/etiologia , Hipersensibilidade Respiratória/imunologia , Traqueia/efeitos dos fármacosRESUMO
1. The effects of the xanthine, theophylline, a non-selective phosphodiesterase (PDE) inhibitor, and the phosphodiesterase type 4 (PDE 4) inhibitor, rolipram, were evaluated in a model of antigen-induced airway responses in the allergic rabbit. 2. Adult litter-matched NZW rabbits (2.5-3.9 kg), immunized within 24 h of birth with Alternaria tenuis antigen, were pretreated twice daily for 3 days with theophylline (3 mg kg-1, i.p) or rolipram (1 mg kg-1, i.p) prior to antigen challenge (Alternaria tenuis). For each drug-treated group, a parallel group of rabbits were pretreated with the appropriate vehicle. In all groups airway responsiveness to inhaled histamine and bronchoalveolar lavage (BAL) was performed 24 h before and after antigen-challenge. 3. Basal lung function in terms of resistance (RL, cmH2O 1(-1)s-1) and dynamic compliance (Cdyn, ml cmH2O-1) were unaltered by pretreatment with theophylline or rolipram compared to their respective vehicles 24 h prior to or post antigen challenge. 4. The acute bronchoconstriction induced by inhaled Alternaria tenuis aerosol was unaffected by pretreatment with theophylline or rolipram. 5. Airway hyperresponsiveness to inhaled histamine was indicated by reduced RL PC50 (2.4-3.5 fold) and Cdyn PC35 (2.5-2.6 fold) values 24 h after antigen challenge. Treatment with rolipram, but not theophylline, prevented the increase in responsiveness to inhaled histamine 24 h after antigen challenge. 6. Total cells per ml of BAL fluid increased 24 h after antigen challenge due to the recruitment of neutrophils and eosinophils. Antigen-induced increases in pulmonary neutrophils were unaffected; however, eosinophils were reduced 57.5% in theophylline and 82% in rolipram-treated rabbits. 7. Inhalation of Alternaria tenuis aerosol elicits an acute bronchoconstriction, followed 24 h later by an increased responsiveness to inhaled histamine and pulmonary neutrophil and eosinophil recruitment in the immunized rabbit. With the dosing regimes used, both rolipram and theophylline inhibited eosinophil recruitment, whilst only rolipram prevented the development of airway hyperresponsiveness. Neither agent inhibited the acute bronchoconstriction due to inhaled antigen.
Assuntos
Anti-Inflamatórios/farmacologia , Espasmo Brônquico/prevenção & controle , Inibidores de Fosfodiesterase/farmacologia , Pirrolidinonas/farmacologia , Hipersensibilidade Respiratória/prevenção & controle , Teofilina/farmacologia , Resistência das Vias Respiratórias , Alternaria/imunologia , Animais , Anti-Inflamatórios/uso terapêutico , Antígenos de Fungos , Asma/imunologia , Espasmo Brônquico/etiologia , Espasmo Brônquico/imunologia , Líquido da Lavagem Broncoalveolar/citologia , Líquido da Lavagem Broncoalveolar/imunologia , Feminino , Histamina , Contagem de Leucócitos , Complacência Pulmonar , Masculino , Inibidores de Fosfodiesterase/uso terapêutico , Pirrolidinonas/uso terapêutico , Coelhos , Hipersensibilidade Respiratória/etiologia , Hipersensibilidade Respiratória/imunologia , Rolipram , Teofilina/uso terapêuticoRESUMO
Products derived from arachidonic acid (AA) via both the cyclo-oxygenase and lipoxygenase pathways play a role in inflammation: prostaglandins (PGs), particularly PGE2, contribute to the formation of oedema, erythema and hyperalgesia whereas leukotriene B4 (LTB4), a product of the 5' lipoxygenase, may modulate the recruitment of leukocytes. We have previously reported that supplementation of a standard rat diet with eicosapentaenoic acid (EPA) caused a significant increase in the formation of LTB5, which is less active biologically than LTB4, and a decrease in the synthesis of LTB4 by stimulated leukocytes. Now we have assessed the effects of administration of highly purified EPA ethyl ester (79% pure), in two models of acute inflammation. Supplementation of a standard rat diet with 240 mg/kg/day EPA for 4 weeks significantly decreased the concentration of PGE2 and TXB2 in inflammatory exudate derived from implantation of carrageenin impregnated sponges: neither the concentration of LTB4 nor the cell number were reduced significantly. Triene prostaglandins were not detected in the exudate, however, significant levels of LTB5 were present. In the second model, oedema induced by injection of carrageenin into rat paws was significantly reduced in animals fed an EPA-rich diet. Supplementation of the diet with EPA could, by mainly reducing the synthesis of prostaglandins, offer a novel and non-toxic approach to the modulation of an inflammatory response.
Assuntos
Ácido Eicosapentaenoico/fisiologia , Inflamação/fisiopatologia , Leucotrieno B4/biossíntese , Prostaglandinas/biossíntese , Animais , Dieta , Exsudatos e Transudatos/citologia , Exsudatos e Transudatos/metabolismo , Contagem de Leucócitos , Ratos , Tromboxanos/biossínteseRESUMO
We present the in vitro characterization of a novel phosphodiesterase type 4 inhibitor, CDP840 (R-[+]-4-[2-¿3-cyclopentyloxy-4-methoxyphenyl¿-2-phenylethyl]pyridine), which has shown efficacy in a phase II allergen challenge study in asthmatics without adverse effects. CDP840 potently inhibits PDE-4 isoenzymes (IC50 2-30 nM) without any effect on PDE-1, 2, 3, 5, and 7 (IC50 > 100 microM). It exhibited no significant selectivity in inhibiting human recombinant isoenzymes PDE-4A, B, C or D and was equally active against the isoenzymes lacking UCR1 (PDE-4B2 and PDE-4D2). In contrast to rolipram, CDP840 acted as a simple competitive inhibitor of all PDE-4 isoenzymes. Studies with rolipram indicated a heterogeneity within all the preparations of PDE-4 isoenzymes, indicative of rolipram inhibiting the catalytic activity of PDE-4 with both a low or high affinity. These observations were confirmed by the use of a PDE-4A variant, PDE-4A330-886, which rolipram inhibited with low affinity (IC50 = 1022 nM). CDP840 in contrast inhibited this PDE-4A variant with similar potency (IC50 = 3.9 nM), which was in good agreement with the Kd of 4.8 nM obtained from [3H]-CDP840 binding studies. Both CDP840 and rolipram inhibited the high-affinity binding of [3H]-rolipram binding to PDE-4A, B, C, and D with similar Kd app (7-19 nM and 3-5 nM, respectively). Thus, the activity of CDP840 at the [3H]-rolipram binding site was in agreement with the inhibitor's activity at the catalytic site. However, rolipram was approximately 100-fold more potent than CDP840 at inhibiting the binding of [3H]-rolipram to mouse brain in vivo. These data clearly demonstrate that CDP840 is a potent selective inhibitor of all PDE-4 isoenzymes. In contrast to rolipram, CDP840 was well-tolerated in humans. This difference, however, cannot at present be attributed to either isoenzyme selectivity or lack of activity in vitro at the high-affinity rolipram binding site (Sr).
Assuntos
3',5'-AMP Cíclico Fosfodiesterases/antagonistas & inibidores , Inibidores de Fosfodiesterase/farmacologia , Piridinas/farmacologia , 3',5'-AMP Cíclico Fosfodiesterases/genética , Animais , Ligação Competitiva , Encéfalo/efeitos dos fármacos , Encéfalo/enzimologia , Catálise/efeitos dos fármacos , AMP Cíclico/biossíntese , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4 , Cobaias , Humanos , Masculino , Camundongos , Inibidores de Fosfodiesterase/química , Ligação Proteica/efeitos dos fármacos , Piridinas/química , Pirrolidinonas/antagonistas & inibidores , Pirrolidinonas/metabolismo , Rolipram , TrítioRESUMO
In conclusion, we have described a novel series of acetohydroxamic acids that are potent and selective inhibitors of arachidonate 5-lipoxygenase in vitro and in vivo. In addition, we have shown that these compounds attenuate "leukotriene-dependent" anaphylactic bronchospasm, the accumulation of inflammatory leukocytes, and the development of fever in experimental models. It now remains to be determined if these compounds have any therapeutic value in man.
Assuntos
Anafilaxia/metabolismo , Araquidonato Lipoxigenases/antagonistas & inibidores , Ácidos Araquidônicos/metabolismo , Ácidos Hidroxâmicos/farmacologia , Inibidores de Lipoxigenase , Ácido 5,8,11,14-Eicosatetrainoico/farmacologia , Anafilaxia/fisiopatologia , Animais , Araquidonato 5-Lipoxigenase/metabolismo , Ácido Araquidônico , Testes de Provocação Brônquica , Espasmo Brônquico/fisiopatologia , Febre/fisiopatologia , Mucosa Gástrica/efeitos dos fármacos , Cobaias , Humanos , Inflamação , Leucócitos/enzimologia , Leucotrieno B4/fisiologia , Masoprocol/farmacologia , Ratos , SRS-A/fisiologiaRESUMO
Superfusion of lung parenchymal strips or tracheal strips from the guinea-pig with effluent from perfused isolated lungs reduced the contractions elicited by leukotriene C4 (LTC4) and leukotriene D4 (LTD4) but not those elicited by acetylcholine (ACh). Incubation of the lung perfusate for 15 min at 37 degrees C removed the inhibitory effect, as did treatment of the lungs with indomethacin (0.5 microgram ml-1) suggesting that a labile cyclo-oxygenase product was causing the inhibition. Addition of prostacyclin (0.8-5.0 ng ml-1) to the fluid superfusing tracheal and parenchymal strips produced a dose-related decrease in leukotriene-induced contractions, whereas 6-oxo-PGF1 alpha and PGE2 were inactive. Contractions of tracheal strips induced by LTC4 were significantly enhanced by infusion of PGF2 alpha. Parenchymal strips usually developed tachyphylaxis to repeated doses of LTC4. This tachyphylaxis has less evident in the presence of indomethacin (2 micrograms ml-1). Contractions of parenchymal and tracheal strips to histamine, acetylcholine and the stable thromboxane mimetic U-46619 were unaffected by infusion of prostacyclin (5 ng ml-1). These results indicate that prostacyclin selectively antagonises airway smooth muscle reactivity to LTC4 and LTD4 by a mechanism which remains to be elucidated.
Assuntos
Epoprostenol/farmacologia , Músculo Liso/fisiologia , SRS-A/farmacologia , Acetilcolina/farmacologia , Animais , Cobaias , Técnicas In Vitro , Indometacina/farmacologia , Pulmão/fisiologia , Masculino , Contração Muscular/efeitos dos fármacos , Perfusão , Traqueia/fisiologiaRESUMO
Some non-steroid anti-inflammatory drugs which inhibit arachidonate cyclo-oxygenease have been examined for their effects on leukocyte migration, prostaglandin production and oedema formation in carrageenin-induced inflammation in the rat. At doses which inhibited oedema, all the drugs tested caused a dose-dependent reduction in numbers of leukocytes and prostaglandin concentrations in 24-h inflammatory exudates. At lower doses, indomethacin, aspirin, sodium salicylate, flurbiprofen and phenylbutazone significantly potentiated leukocyte migration by 20-70%. Ibuprofen, naproxen and BW755C reversed the indomethacin-induced increase in leukocyte accumulation. BW755C inhibits the generation of chemotactic lipoxygenase products and it is possible that the effects of all these drugs on leukocyte migration are mediated through the lipoxygenase pathway of arachidonic acid metabolism.