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.