title: Intramuscular relative dose response (RDR) determination of liver vitamin A stores in rats.
abstract: This study questioned whether the relative dose response (RDR) method to detect liver stores of vitamin A could be used by intramuscular administration of the vitamin. Vitamin A-deficient and reference rat serum retinol levels were determined by HPLC at zero time and then again 5 h after an intramuscular injection of 5.25 mumol/kg retinyl palmitate. The RDR percentage was calculated: [(A5-A0)/(A5)] x 100. The 5-h RDR was determined in 20 deficient and 16 reference diet rats and a clear relationship to liver retinyl palmitate concentration was demonstrated. At a liver retinyl palmitate concentration of less than 0.105 mumol/g, all RDR values were greater than 20%. When the liver retinyl palmitate was greater than 0.122 mumol/g the RDR was less than 20%. This study suggests that the intramuscular RDR is a valid tool for estimating liver retinyl palmitate in populations in which the oral RDR cannot be administered.
authors.affiliation: Department of Pediatrics, University of Wisconsin, Madison 53715.
authors.forename: R D
authors.initials: RD
authors.lastname: Zachman
authors.forename: X M
authors.initials: XM
authors.lastname: Chen
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004224:Diterpenes; D004305:Dose-Response Relationship, Drug; D007273:Injections, Intramuscular; D008099:Liver / Q000737:chemistry*; D008297:Male; D011897:Random Allocation; D051381:Rats; D011919:Rats, Inbred Strains; D000084562:Retinyl Esters; D013047:Specific Pathogen-Free Organisms; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D004224:Diterpenes; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate