RESUMO
Lipoxin A (LXA) is a novel eicosanoid, generated by the interactions of lipoxygenases, which has a variety of biological actions. When added to human polymorphonuclear leukocytes, LXA stimulated thromboxane formation which was monitored as TxB2 by radioimmunoassay. The compound augmented the formation of TxA2 stimulated by the ionophore of divalent cations (A23187). Formation of thromboxane was inhibited by two non-steroidal anti-inflammatory drugs (i.e. indomethacin and proglumetacin). Results of the present study indicate that LXA can provoke the release and transformation of endogenous arachidonic acid to thromboxane. Moreover, they suggest a relationship between lipoxin A and the formation of cyclooxygenase pathway products.
Assuntos
Ácidos Hidroxieicosatetraenoicos/farmacologia , Lipoxinas , Neutrófilos/metabolismo , Tromboxano A2/sangue , Tromboxano B2/sangue , Calcimicina/farmacologia , Humanos , Ácidos Indolacéticos/farmacologia , Indometacina/farmacologia , Neutrófilos/efeitos dos fármacosRESUMO
The effects of pulsed extremely low frequency electromagnetic fields on human peripheral blood lymphocyte mitogenesis induced by phytohaemoagglutinin, concanavalin A or calcium ionophore A23187 were studied. The dependence of the field effect on mitogen concentrations was investigated. Field exposure produced strong inhibition of DNA synthesis when optimal doses of mitogens were used, confirming our previous findings. Opposite effects were observed at suboptimal concentration of mitogens. Experiments performed by exposing cell cultures to the field for short periods indicated that a field application of at least 6 h is needed to influence irreversibly lymphocyte blastogenesis.
Assuntos
Calcimicina/farmacologia , Concanavalina A/farmacologia , Campos Eletromagnéticos , Fenômenos Eletromagnéticos , Ativação Linfocitária , Fito-Hemaglutininas/farmacologia , Cálcio/metabolismo , Células Cultivadas , Replicação do DNA/efeitos dos fármacos , Replicação do DNA/efeitos da radiação , Relação Dose-Resposta a Droga , Humanos , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/efeitos da radiação , Linfócitos/efeitos dos fármacos , Linfócitos/metabolismo , Linfócitos/efeitos da radiação , Fatores de TempoRESUMO
The DNA synthesis of lymphocytes triggered by phytohemagglutinin or phorbol-myristate-acetate is strongly reduced by the externally applied electromagnetic field (ELF). Ca2+ uptake by stimulated lymphocytes is also reduced by ELF. The effect appears to be synergistic with that of the well-known calcium blocker agent, verapamil.
Assuntos
Cálcio/metabolismo , Fenômenos Eletromagnéticos , Ativação Linfocitária/efeitos dos fármacos , Humanos , Linfócitos/metabolismo , Fito-Hemaglutininas/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Timidina/metabolismo , Verapamil/farmacologiaRESUMO
Blastogenesis of human peripheral blood lymphocytes stimulated in vitro by non-specific mitogens (PHA, ConA, PWM) upon exposure to extremely low frequency EMF has been studied. Different frequencies of square waveforms have been used. PHA-stimulation resulted in strong inhibitions as measured by [3H]thymidine incorporation. A frequency window (3-50 Hz) within which ConA-induced blastogenesis was significantly inhibited has been individuated. The mitogenic effect of PWM was significantly affected only at 3 Hz.
Assuntos
Campos Eletromagnéticos , Fenômenos Eletromagnéticos , Lectinas/farmacologia , Ativação Linfocitária , Adulto , Células Cultivadas , Concanavalina A/farmacologia , Humanos , Fito-Hemaglutininas/farmacologia , Mitógenos de Phytolacca americana/farmacologia , Timidina/metabolismoRESUMO
High concentrations of the non-steroid anti-inflammatory drugs, alone and in association, reduce the blastogenesis of human lymphocytes in vitro. This effect is probably due to the toxicity of these agents and not to the inhibition of prostaglandin (PG) prosuction. Therefore drugs, such as, salicylates and associations of salicylates with other non-steroid anti-inflammatory drugs, which have a weak action on PG-synthesis, also inhibit proliferation of lymphocytes.