The Effect of Pinealectomy and of Lesions in the Subcommissural Body on the Rate of Aldosterone Secretion by Rat Adrenal Glands in Vitro

Abstract

The rate of aldosterone secretion by adrenal glands in vitro is used as an index of aldosterone secretion in vivo . In small animals, such as the rat, a quantitative determination of aldosterone in blood is handicapped by the low concentration of this hormone in peripheral blood. The concentration of aldosterone in the adrenal venous effluent is much higher, but adrenal vein cannulation is inevitably associated with severe traumatization and blood loss. The isolation of aldosterone from blood is time consuming and needs stringent isolation procedures. In the study described in the chapter, it was observed that noxious stimuli that increased corticoidogenesis in vitro did not alter the rate of aldosterone secretion in vitro . Hypophysectomy decreased the corticoid production in vitro , while increasing the secretion of aldosterone in vitro . The rate of aldosterone secretion in vitro in adrenals of rats subjected to hemorrhage or experimental nephrosis rose, thereby indicating that stimuli that are known to increase aldosterone secretion in vivo also augment the aldosterone secretion in vitro . Accordingly, the rate of aldosterone secretion was measured in pinealectomized rats and in animals with lesions in the subcommissural body. Aldosterone secretion in vitro was not materially affected by pinealectomy, while lesions in the subcommissural body tended to decrease the basal aldosterone secretion rate. However, the increase in aldosterone secretion, induced by experimental nephrosis, was not abolished by pinealectomy or lesions.