Artículos de revistas
Effects Of Escapable And Inescapable Foot-shock On Rat Atrial Beta-adrenoceptors.
Registro en:
Pharmacology, Biochemistry, And Behavior. v. 44, n. 4, p. 869-75, 1993-Apr.
0091-3057
8385784
Autor
Bassani, R A
Bassani, J W
Institución
Resumen
The chronotropic responsiveness to norepinephrine (NE) and isoproterenol (ISO) was determined in right atria isolated from rats submitted to repeated escapable or inescapable foot-shock. Significant postjunctional supersensitivity to ISO, but not to NE, was observed in both groups. No significant change in the pA2 value of metoprolol (a selective beta 1-adrenoceptor antagonist) was detected. However, a decrease of the maximum response to soterenol, a partial agonist at beta 1-adrenoceptors, occurred only after inescapable foot-shock. The enhanced sensitivity to ISO was abolished by butoxamine (a selective beta 2-adrenoceptor antagonist) and accompanied by a marked increase in the pA2 value of this antagonist. We conclude that the ability to control the shock prevented the down-regulation of the pacemaker beta 1-adrenoceptors but not the increased participation of beta 2-adrenoceptors in the response of the rat sinoatrial node to catecholamines after repeated foot-shock. 44 869-75