Action of Adrenal Cortical Steroids and Nor-Epinephrine on Vascular Responses of Stress in Adrenalectomized Rats

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Abstract
The adrenalectomized animal dies in circulatory failure in response to stresses to which the normal can adjust. To evaluate the ability of the adrenalectomized animal to maintain its peripheral resistance, the Chambers-Zweifach rat mesoappendix prepn. was utilized to observe blood flow under various exptl. conditions. From these direct microscopic observations, the following was demonstrated: Blood vessels of the mesoappendix of the adrenalectomized rat became refractory to repeated topical appln. of nor-epinephrine, while those of normal controls retained their sensitivity. Responsiveness to nor-epinephrine was restored by the topical appln. of aqueous adrenal cortical extracts. Formalin injn. did not impair circulation in the mesoappendix of normal rats, but induced a sluggishness of flow, terminating in stasis and complete cessation of flow prior to death, in the mesoappendix of the adrenalectomized rat. These changes were prevented by Dibenamine. Dibenamine also prolonged the survival time of adrenalectomized rats which were given lethal amts. of formalin. The early stage of Dibenamine blockade of adrenergic agents was overcome by adequate amounts of adrenal cortical extracts in both normal and adrenalectomized rats.