EFFECT OF HYDRALAZINE AND OTHER DRUGS ON KINETICS OF PROCAINAMIDE ACETYLATION BY RAT-LIVER AND KIDNEY N-ACETYLTRANSFERASE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 204  (1) , 212-218
Abstract
The cytosol fraction (100,000 .times. g) of tissue homogenates served as the source of N-acetyltransferase. Of the tissues studied the liver possessed the greatest acetylase activity followed by the kidney, lung, intestine and spleen. The apparent procainamide Km for liver and kidney was 2.03 .times. 10-4 and 2.09 .times. 10-4 M, respectively, in the presence of 4.2 .times. 10-4 M acetyl CoA. The liver Km for procainamide with infinite acetyl CoA concentration was 4.36 .times. 10-3 M. The liver Km for acetyl CoA in the presence of infinite PA concentration was 2.44 .times. 10-3 M. Hydralazine, p- aminobenzoic acid, isoniazid and sulfapyridine competitively inhibited procainamide acetylation by liver and kidney N-acetyltransferase.