Cytochemical localization of calcium in mitochondria of regenerating rat adrenal cortex. A study of adrenal regeneration hypertension.

The distribution of calcium in the mitochondria of the adrenal gland was studied during development of adrenal regeneration hypertension. Electron opaque precipitate (calcium antimonate) was localized predominantly in the intercristal space within mitochondria and in cisternae of smooth endoplasmic reticulum. Stereological techniques were employed to quantitate the volume per cell of precipitate. Compared to the zona glomerulosa or zona fasciculata of controls, the volume per cell of electron opaque precipitate in mitochondria of the regenerating gland was significantly reduced at 5 and 14 days after enucleation. By 21 days, the volume of mitochondrial precipitate per cell, while more than that in zona glomerulosa cells, was less than in mitochondria from control zona fasciculata cells. As a comparison, normal rats were treated with ACTH or were hypophysectomized. ACTH-treatment did not greatly increase the precipitate associated with mitochondria in the zona fasciculata. Mitochondria in the zona fasciculata of hypophysectomized rats however showed a significant reduction in precipitate per cell correlating with a significantly reduced volume of mitochondria per cell as compared to those of control zona fasciculata cells. Giant mitochondria were observed in hypophysectomized animals. Volume of precipitate per cell associated with smooth endoplasmic reticulum was increased slightly, but significantly, as compared to that in controls treated with ACTH, whereas in hypophysectomized rats, it was decreased significantly. Adrenocortical cells arising from the zona glomerulosa and sub zona glomerulosa region differentiate to zona fasciculata cells during regeneration and may have an altered capacity to concentrate calcium. Change in intramitochondrial calcium may be correlated with the reduced formation of corticosterone from its precursor, deoxycorticosterone, thereby contributing to the pathogenesis of adrenal regeneration hypertension.