Exchange of isethionate between blood and tissues in adult and 7-day-old mice

[14C] Isethionate was injected intramuscularly into adult and 7-day-old mice and the distribution of the label in the blood, brain, heart, liver and spleen was determined. Endogenous isethionate in these tissues was determined and approximate exchange rates calculated from the endogenous isethionate tissue levels and specific radioactivities after certain time intervals. The concentration of isethionate was higher and its exchange rates between plasma and tissues faster in the adult mice than in the 7-day-old mice. A close correlation between isethionate transport rates and tissue levels in vivo was obtained in both age groups. The tissues eliminated isethionate rapidly, even faster in the adult than in the 7-day-old mice. The elimination of isethionate showed three different components, fast, intermediate and slow, in the heart, liver and spleen of the adult mice, but only two components, fast and slow, in the other cases.