Hypertension from compression and/or enucleation of the adrenal glands in the rat

Previos studies have shown that compression of the adrenal glands is as effective as adrenal enucleation in causing hypertension in rats. Unilateral adrenal enucleation is ineffective, however, if a normal contralateral adrenal gland is present. The studies reported herein demonstrate that unilateral compression also fails to cause hypertension in the presence of a normal contralateral gland. When present singly, either enucleate or compressed adrenals cause hypertension; when either is present with a normal contralateral gland, the blood pressure is unaffected. When compressed or enucleate glands constitute the pair, in any combination, hypertension ensues. However, whereas an enucleate gland remains extremely atrophic in the presence of a normal gland, compressed glands attain a much larger size under this circumstance. Furthermore, a compressed gland is less inhibitory to the regeneration of a contralateral enucleate gland than is a normal adrenal. Whereas enucleate glands, whether bilateral or unilateral, are always smaller than normal glands, compressed adrenals may be enlarged. The hypertensogenic function of compressed adrenals is, like that of enucleate glands, suppressed by the presence of a normal gland. The growth response of compressed or enucleate glands, whether bilateral or single, appears to depend upon the degree of injury inflicted upon them. There is a considerable discrepancy in the size of individual members of a pair when one or both have been injured, that members of a normal pair do not exhibit.