Vanderlei, L. C M [UNESP]Marcondes, F. K.Lanza, L. L BSpadari-Bratfisch, R. C.2014-05-272014-05-271996-11-23Canadian Journal of Physiology and Pharmacology, v. 74, n. 6, p. 670-678, 1996.0008-4212http://hdl.handle.net/11449/64878We investigated the mechanisms of the alterations in sensitivity to catecholamines in right atria from female rats exhibiting regular 4-day estrous cycles after three foot-shock sessions at estrus, metestrus, and diestrus or at diestrus, proestrus, and estrus. Right atria from stressed rats sacrificed at diestrus showed subsensitivity to noradrenaline and adrenaline. After in vitro sympathetic denervation (38 μM 6-hydroxydopamine) plus inhibition of neuronal reuptake (0.1 μM desipramine) subsensitivity to noradrenaline was abolished, but it was again evident when extraneuronal uptake was also inhibited (10 μM phenoxybenzamine and 30 μM corticosterone). The same pretreatment abolished the subsensitivity to adrenaline. After addition of 1 μM butoxamine, a β2-adrenoceptor antagonist, the tissues from stressed rats were subsensitive to adrenaline. Right atria from stressed rats sacrificed at estrus did not show any alteration in sensitivity to catecholamines. We conclude that after foot-shock stress, right atria from female rats sacrificed at diestrus showed subsensitivity of the chronotropic response to catecholamines as a result of a conformational alteration of β1-adrenoceptors, simultaneously with an increase in β2-adrenoceptor-mediated response. The mechanisms seem to be similar to those which underlie stress-induced alterations in catecholamine sensitivity in right atria from male rats. However, during estrus there are some protective factors that prevent the effects of stress on right atria.670-678engAdrenalineDiestrusEstrusFemale ratsFoot-shock stressNoradrenalineSubsensitivityadrenalinbutoxaminecatecholamine derivativecorticosteronedesipraminenoradrenalinoxidopaminephenoxybenzamineanimal experimentanimal tissuechronotropismcontrolled studydenervationdiestrusdrug sensitivityestrus cyclefemaleheart right atriumin vitro studynonhumanpriority journalratstressAdrenergic beta-AntagonistsAnimalsAtrial FunctionButoxamineElectroshockEpinephrineFemaleHeart AtriaHeart RateNorepinephrineRatsRats, WistarStressArtigo10.1139/cjpp-74-6-670WOS:A1996VP80100008Acesso restrito2-s2.0-00298199145860525135106995