Abstract
After the intraperitoneal administration of potassium L-serine O[S35]-sulfate to male and female rats most of the radioactivity appears in the urine within 24 hours. Up to 75% of the administered dose appears in the urine as inorganic [S35]sulfate. Of the S - activity recovered in the urine up to 92% was in the inorganic sulfate fraction, the remainder being associated with the ester sulfate fraction. Fecal preparations are capable of desulfating L-serine O[S35]-sulfate in vitro, 30% of the available S35 appearing as inorganic [S35]-sulfate in 24 hours at 20[degree]. The administration of antibacterial agents to rats before the intraperitoneal injection of L-serine O[S35]-sulfate results in a decrease in the level of S35-activity associated with inorganic (SO4) fraction. After the administration of the S35-labelled ester, chromatographic examination of the urines of rat, mouse and guinea pig shows, in each case, a complex pattern of S35-labelled materials identical with that obtained after the injection of sodium [S35]sulfate.