Time course of fecal steroid-C14 excretion in various rodents

Abstract

A study was made of the rates of fecal excretion of sterol-C14 and bile acid-C14 during a 7-day period after an intraperitoneal injection of dl-mevalonic acid-2-C14. The percentages of fecal C14 steroids excreted as bile acid-C14 by several species were: mouse, 51%; hamster, 62%; rat, 62%; guinea pig, 33%; gerbil, 66%; and rabbit, 56%. The balance of excretion was neutral sterol-C14. The ratios of fecal bile acid-C14 to neutral sterol-C14 varied with time. The animals can be divided into three groups in respect to rate of excretion: rat and mouse had high excretion rates; gerbil an intermediate rate; while hamster, guinea pig, and rabbit had low rates. The amounts of C14 sterols retained in serum, liver, and carcass after 7 days were determined. The highest retained activity was in guinea pig and rabbit, the lowest in rat tissues. The sum of excreted steroid-C14 and retained sterol-C14, which equals total synthesized steroid-C14, was calculated. Guinea pig, rat, and mouse incorporated the greatest amount of C14; gerbil, an intermediate amount; and hamster, the smallest amount.