Progesterone secretion by adrenal glands of hamsters and comparison of ACTH influence in rats and hamsters.

Studies were designed to determine a) if adrenal glands of hamsters secrete progesterone (PROG), b) the effects of adrenocritocotropin (ACTH) administration on adrenocortial function of rats and hamsters under the surgical conditions necessary for collection of adrenal venous blood from the left renal vein, and c) the effects of blood loss during sample collection. PROG was quantitated by the competitive protein-binding method after extraction and separation by sephadex LH-20 column chromatography. The presence of interfering quantities of androstenedione necessitated two column chromatographic steps. Glucocorticoids (11-OHCS) were determined fluorometrically. PROG was detected in adrenal venous plasma of female hamsters. The PROG concentration and secretory rate were 91 +/- 12 ng/ml and 4 +/- 1 ng/min, respectively, while the peripheral plasma level of the same animals was 2 +/- 0.2 ng/ml, indicating that the adrenal glands of female hamsters are capable of secreting PROG. ACTH administration increased PROG secretory rates in both hamsters (3 +/- 1 to 14 +/- 3 ng/min) and rats (62 +/- 9 to 152 +/- 32 ng/min) on estrus, as well as increasing the 11-OHCS secretory rate of hamsters (16 +/- 1 to 33 +/- 4 ng/min), but not of rats. The greater increase in PRCC than in 11-OHCS secretion may be related to excess PROG formation relative to the capacity of the 17alpha- or 21-hydroxylating enzyme systems. The adrenal venous PROG concentration and secretory rate of female hamsters infused with 10% dextran while collecting adrenal venous blood did not differ significantly from those of the non-infused animals, suggesting that this amount of blood loss (1 ml) does not influence PROG secretion.