Progesterone, some Progesterone Derivatives and Urinary Digoxin‐Like Substances from Pregnant Women in Radioimmuno‐ and ⁸⁶Rb‐Uptake Assays of Digoxin

Abstract

Progesterone and some derivatives were tested in a radioimmunoassay (RIA) of digoxin and in a bioassay measuring the 86Rb-uptake into red blood cells as an index of Na+, K+-ATPase activity. The digitalis-like activity of the hormones was compared with that found in chromatographic fractions of material extracted from the urines of pregnant women at term. Progesterone at concentrations greater than 10(-6) M cross-reacted in the RIA, and at 10(-3) M it decreased 86Rb-uptake by 18%. The anaesthetic progesterone derivates 5 alpha-pregnane-3 alpha-ol-20-one and 5 alpha-pregnane-3,20-dione crossreacted to a lesser degree in the RIA and lacked effect in the bioassay. Similar results were obtained with pregnandiol-glucuronide, the major urinary metabolite of progesterone. In contrast, several fractions of the urinary material had significant effects in both assays. It is concluded that the digitalis-like activity of progesterone is not coupled to properties associated with its anaesthetic effects. Furthermore, although progesterone may account for a part of the endogenous digoxin-like substances in serum of neonates and pregnant women, neither progesterone proper nor pregnandiol-glucuronide explains the great amount of digoxin-like substances found in the urines.

Pregnancy induced hypertension and sodium pump function in erythrocytes

“…However, as both blood pressure and erythrocyte sodium fall progressively in normal pregnancy, a positive correlation is unlikely. It is also unlikely that any circulating digoxin‐like substance plays any functional role during normal pregnancy (Vinge et al . 1988; Gonzalez et al .…”

Endogenous Digoxin-Like Immunoreactivity in FoUicular Fluid and in vitro Fertilization

“…However, very high concentrations of progester one and its metabolites, at 10~4 to 10~3 M, may inhibit the digoxin tracer by 20-50% [11], The concentration of progesterone in the stimulated follicular fluid is at 10~6 to 10-5 zW [12,13], which may be responsible for up to 5-15% of DLIF activity as measured by our RIA method [11] and is not the cause for the very high levels of DLIF in the follicular fluid.…”