title: Active versus passive absorption kinetics as the basis for selective protection of normal tissues by S-2-(3-aminopropylamino)-ethylphosphorothioic acid.
abstract: Through an in vivo and in vitro analysis of the absorption kinetics of S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) in the normal tissues and solid tumors of mice, rats, and rabbits, it has been demonstrated that normal tissues actively concentrate WR-2721 against a concentration gradient, whereas solid tumors passively absorb it, or, if active concentration of WR-2721 is present in tumors, it operates at a far reduced rate relative to normal tissues. These observations can account for the ability of WR-2721 to selectively protect normal tissues against both radiation and alkylating agent injury.
mesh_terms: D000042:Absorption; D000230:Adenocarcinoma / Q000378:metabolism; D004999:Amifostine / Q000378:metabolism*; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D005260:Female; D008099:Liver / Q000098:blood supply / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D051379:Mice; D009946:Organothiophosphorus Compounds / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D014018:Tissue Distribution
chemical_list: D009946:Organothiophosphorus Compounds; D004999:Amifostine