Plasma C-21 steroids in conscious pregnant and non-pregnant rabbits with chronic catheterization of the femoral artery and the portal and hepatic veins.

In conscious non-pregnant (n = 8) and pregnant (n = 7) rabbits, blood samples were collected by chronic catheterization of the femoral artery and the hepatic and portal veins. In the non-pregnant group, deoxycorticosterone (DOC), corticosterone (B), cortisone (E) and cortisol (F) were determined by RIA. In the pregnant group, progesterone (P) and 20 alpha-dihydroprogesterone were also radioimmunoassayed. The arterio-venous difference of the levels observed has demonstrated the role of the liver and the splanchnic area in steroid metabolism. Moreover, the comparison of the steroid pattern in the two groups showed that gravidity was characterized by a marked increase of F and E but not of B and DOC levels. Thus, the ratio of F/B in the femoral artery was markedly increased in the pregnant animals; this ratio ranged from 0.20 to 1.12 in the non-pregnant group, and from 1.3 to 12.5 in the pregnant group.