Functional beta(2)-adrenoceptors in rat left atria: effect of foot-shock stress

Date
2017Author
Moura, Andre Luiz de [UNIFESP]
Hyslop, Stephen
Grassi-Kassisse, Dora M.
Spadari, Regina Celia [UNIFESP]
Type
ArtigoISSN
0008-4212DOI
10.1139/cjpp-2016-0622Metadata
Show full item recordAbstract
Altered sensitivity to the chronotropic effect of catecholamines and a reduction in the beta(1)/beta(2)-adrenoceptor ratio have previously been reported in right atria of stressed rats, human failing heart, and aging. In this report, we investigated whether left atrial inotropism was affected by foot-shock stress. Male rats were submitted to 3 foot-shock sessions and the left atrial inotropic response, adenylyl cyclase activity, and beta-adrenoceptor expression were investigated. Left atria of stressed rats were supersensitive to isoprenaline when compared with control rats and this effect was abolished by ICI118,551, a selective beta(2)-receptor antagonist. Schild plot slopes for the antagonism between CGP20712A (a selective beta(1)-receptor antagonist) and isoprenaline differed from unity in atria of stressed but not control rats. Atrial sensitivity to norepinephrine, as well as basal and forskolin-or isoprenaline-stimulated adenylyl cyclase activities were not altered by stress. The effect of isoprenaline on adenylyl cyclase stimulation was partially blocked by ICI118,551 in atrial membranes of stressed rats. These findings indicate that foot-shock stress equally affects inotropism and chronotropism and that beta(2)-adrenoceptor upregulation contributes to the enhanced inotropic response to isoprenaline.
Citation
Canadian Journal of Physiology and Pharmacology. Ottawa, v. 95, n. 9, p. 999-1008, 2017.Keywords
Adenylate cyclaseCGP20712A
Foot-shock stress
Forskolin
Inotropic response
Isoprenaline
Left atria
ICI118,551
Sponsorship
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Collections
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