title: The availability of inorganic sulphate in blood for sulphate conjugation of drugs in rat liver in vivo. (35S)Sulphate incorporation into harmol sulphate.
abstract: 1. When Na235SO4 is injected intravenously in rats, it is immediately available for sulphate conjugation of the phenolic drug harmol (7-hydroxyl-1-methyl-9H-pyrido[3,4-b]indole) in the liver. This was established by following the time course of the biliary excretion of the sulphate conjugate of harmol, and the incorporation of [35S]sulphate into harmol sulphate. 2. During the 10min immediately after injection of Na235SO4 re-distribution of [35S]sulphate took place, which resulted in a rapid initial decrease in the plasma concentration of [35S]sulphate; a concomitant decrease in the amount of [35S]sulphate incorporated into harmol sulphate was observed, indicating that the co-substrate of sulphation, adenosine 3'-phosphate 5'-sulphatophosphate, equilibrates rapidly with [35S]sulphate in plasma. 3. The results suggest that the pool size of adenosine 3'-phosphate 5'-sulphatophosphate is very small; therefore the specific radioactivity of [35S]sulphate in plasma determines the specific radioactivity incorporated into sulphate esters at any time.
mesh_terms: D000470:Alkaloids / Q000378:metabolism*; D000818:Animals; D001646:Bile / Q000378:metabolism; D006247:Harmine / Q000031:analogs & derivatives / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D013431:Sulfates / Q000097:blood* / Q000378:metabolism
chemical_list: D000470:Alkaloids; D013431:Sulfates; C001326:harmol; D006247:Harmine