Abstract
Distribution of tritiated esculin (*esculin) in the organs of rats and guinea pigs was investigated following i. v. injection: the maximal incorporation of *esculin into liver and adrenals was seen 4hr after administration, while concentration of *esculin in blood decreased rapidly; kidneys and testicles retained the *esculin for a comparatively long time, though it gradually decreased. The highest radioactivity per 1g of tissue was observed in the adrenals, followed by the kidneys. Nuclear (N), mitochondrial (Mt), microsomal (Ms) and supernatant (S)-fractions were prepared from the homogenate of liver, adrenals, testicles and kidneys of *esculin injected rats by centrifugation and thereafter the time courses of distribution of *esculin in these fractions were investigated. High radioactivity was obtained in Ms- and S-fraction of the liver 30 min after *esculin treatment and 1hr after, in Mtfraction. In the adrenals, the highest incorporation was observed in S-fraction 1 hr after treatment, the Mt-fraction showing an extremely high incorporation 4hr after treatment. Mt- and N-fraction from the testicles revealed a high radioactivity 1hr after injection. Incorporation of *esculin into Mt-fraction from kidney-medulla was extremely high 4 hr after injection, while a low incorporation into each fraction from kidney-cortex was observed, except for the S-fraction where a high incorporation occurred 30min after treatment. Paperchromatography of methanol extracts from urine and feces collected from *esculin administered rats and guinea pigs was carried out. The main excretion in rat urine was esculin within 1 and 4hr after i. v. injection of *esculin, and 20hr later, a substance which showed a higher Rf value than esculetin (substance X). Although the main excretion in urine from *esculin treated rat (oral) was esculin as shown after i. v. injection, esculetin followed next in order. More than 60% of the administered esculin was excreted into the urine of guinea pig within 4hr and 20hr following i. v. injection. On the other hand, major excretions in feces from *esculin injected rats included esculin, esculetin and substance X 1hr and 20 hr after administration. The same tendency was also observed in rats with oral administration, but with an i, v. injection into guinea pigs, the main excretion showed a lower Rf value than esculin, followed by esculetin and a substance.which showed a higher Rf value than esculin, within 20hr after treatment.
