Repeated swimming stress and responsiveness of the isolated rat pacemaker to the chronotropic effect of noradrenaline and isoprenaline: role of adrenal corticosteroids.
1. Repeated swimming stress (three daily sessions) resulted in an increased plasma corticosterone level and subsensitivity of the isolated rat pacemaker to noradrenaline and isoprenaline. 2. Repeated swimming stress was found to decrease the affinity of beta 1-adrenoreceptors for metoprolol. 3. Bilateral adrenalectomy performed 2 days before repeated swimming stress abolished the development of pacemaker subsensitivity to noradrenaline and isoprenaline and the decrease in beta 1-adrenoreceptors affinity for metoprolol. 4. It is concluded that adrenal corticosteroids, at least partially, mediate the swimming stress-induced subsensitivity of the isolated rat pacemaker to noradrenaline and isoprenaline.
Spadari
R C
RC
Department of Physiology and Biophysics, Faculty of Medical Sciences, Universidade Estadual de Campinas, São Paulo, Brazil.
De Moraes
S
S
D000315:Adrenalectomy; D000818:Animals; D003345:Corticosterone / Q000097:blood*; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008790:Metoprolol / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D013312:Stress, Physiological / Q000503:physiopathology*; D013550:Swimming
D011943:Receptors, Adrenergic, beta; D008790:Metoprolol; D007545:Isoproterenol; D003345:Corticosterone; D009638:Norepinephrine