Plasma catecholamines and 11-hydroxycorticosteroids during interaction between hexamethonium and noradrenaline

Intravenous infusion of noradrenaline leads to much higher elevation of concentrations of noradrenaline and adrenaline in the rabbit plasma in the presence than in the absence of hexamethonium. This effect is related to stimulation of the hypophyseal-adrenal axis, as adrenalectomy or hypophysectomy prevents it. The stimulation of the system takes place without involvement of circulatory reflexes. The 11-hydroxycorticosteroid levels in plasma increase also under the influence of the interaction in hypophysectomized animals, but this does not affect the level of noradrenaline. The causes of this phenomenon are discussed in the light of data on inhibitory effect of steroids on the extraneuronal uptake of catecholamines.