Procainamide N-acetyltransferase: modulation by clofibrate and a microsomal form.
1. Detoxification of procainamide by N-acetyltransferase which occurs primarily in the cytoplasmic fraction of the rat liver can be modulated by clofibrate treatment. 2. When the concentration of one of the substrates, procainamide, is 100 microM while the other, acetyl CoA, is 10 or 100 microM, the specific activity is reduced following clofibrate treatment. However, total activity is unchanged because of a 44% increase in cytoplasmic protein. 3. At more physiological levels of the two substrates (10 microM), total enzyme activity is increased from 9.5 +/- 1.5 to 14.0 +/- 1.8 pmol/mg/min, P less than 0.05. 4. A microsomal form of N-acetyltransferase activity is reported which is unaffected by the concentration of acetyl CoA in contrast to the cytoplasmic form.
Kang
E S
ES
Department of Pediatrics, University of Tennessee, Memphis 38163.
Deaton
P R
PR
Epstein
D
D
Ingram
L A
LA
Mirvis
D M
DM
D000120:Acecainide / Q000378:metabolism; D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002994:Clofibrate / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009929:Organ Size / Q000187:drug effects; D011342:Procainamide / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
D011506:Proteins; D000120:Acecainide; D000123:Acetyltransferases; D001191:Arylamine N-Acetyltransferase; D002994:Clofibrate; D011342:Procainamide