ADRENOCORTICAL ACTIVITY AND PERIPHERAL ADRENERGIC RESPONSES IN THE CAT

¹ Department of Pharmacology, Philadelphia College of Pharmacy and Science, Philadelphia, Pennsylvania

It had been proposed that in the absence of adrenal corticoids the threshold for epinephrine and norepinephrine is raised in every biologic reaction in which these substances participate. This study was concerned with the possible relationship between the level of adrenocortical activity and the integrity of the peripheral adrenergic system.

Three groups of male cats were used: corticoid-deficient (bilateral adrenalectomy), hypercorticoid (sham adrenalectomy, followed by administration of ACTH), and control (sham adrenalectomy). Alterations in the level of adrenocortical activity were evidenced by significant changes in serum Na/K ratios. The mean Na/K ratio of the corticoid-deficient group was 71.5% of the control; that of the hypercorticoid group was 128.9% of the control.

Neither the tension (g) developed by the nictitating membrane in response to varying rates of electrical stimulation of the cervical sympathetic trunk, nor the inhibition of evoked postganglionic potentials (superior cervical ganglion) induced by graded doses of l-epinephrine, was significantly altered in the hypercorticoid and corticoid-deficient animals. It is concluded that the proposed permissive or supportive role of the adrenal corticoids is not manifest in regard to these designated sites.