Estresse por natação forçada e supersensibilidade de atrios direitos de ratos ao isoproterenol : papel da corticosterona

Não informado.The effect of stress obtained by repeated forced swimming on the sensitivity of the isolated pacemaker of the rat to the chronotropic effect of isoprenaline (ISO) was studied. Forced swimming stress induces supersensitivity to isoprenaline and a large increase in the plasma leveI of corticosterone. Adrenalectomy or pretreatment of the rats with RU 38486 an antiglucocorticoid compound prevented the development of forced swimming stress-induced supersensitivity to ISO. Administration of the synthetic glucocorticoid compound RU 28362 to rats not submitted to forced swimming stress causes supersensitivity to ISO. Pretreatment of the rats with diazepam or imipramine wich blocked the forced swimminginduced increase ín the plasma leveI of corticosterone abolished the development of pacemaker supersensitivity to ISO. We conc1uded that corticosterone seems to play a critical role in the modulation of the sensitivity of pacemaker beta adrenoceptors to isoprenaline during adaptation to repeated stress