HDCN Article Review/Hyperlink

Hilton PJ, White RW, Lord GA, Garner GV, et al

An inhibitor of the sodium pump obtained from human placenta

Lancet (Aug) 348:303-305 1996

The search for the body's "natural born digoxin" or Na/K sodium pump inhibitor may be nearing its goal. Initial findings of such substances in the blood were greeted with the skepticism, as they may have come from plant derived substances via ingestion of food. However, at the ASH meetings this spring, Bagrov et al. presented their results that humans appear to contain in their plasma and urine a substance similar to that found in toads (marinobufagenin). They also found that "toad-digoxin" had more potent Na/K pump inhibitory effects than ouabain in vascular smooth muscle.

In this paper, Hilton et al, who previously had found a leucocyte Na/K pump inhibitor in umbilical vein blood, looked to human placenta and from there isolated a steroidal substance very similar to the toad hormone. The Na/K pump inhibitor, which was obtained in pure form, was a derivative of bufenolide, and was nearly identical to the substance made by toads, with the exception of one double bond and a hydroxyl group. As the women all denied recent ingestion of toad (frog?) legs, and as the bufalin family of Na/K pump inhibitors is not known to exist in plant or other foods, the long search for an endogenous Na/K pump inhibitor may be over. The novel synthetic pathway for this substance remains to be demonstrated in humans, however. (John T. Daugirdas, M.D., University of Illinois at Chicago)