Reduction by acute restraint stress of noradrenaline sensitivity in the isolated pacemaker of the rat.

Acute restraint stress induced subsensitivity of the isolated pacemaker of the rat to the chronotropic effect of noradrenaline and reduced the affinity of atrial beta 1-adrenoceptors for metoprolol. The effects of restraint stress were abolished two days after bilateral adrenalectomy. The controlled venous infusion of noradrenaline plus adrenaline was without effect on the atrial sensitivity to noradrenaline and the pA2 value of metoprolol. It is concluded that the effects of restraint stress on atrial beta 1-adrenoceptors are mediated at least partially by adrenal corticosteroids.