Sulfonamide acetylation in isolated rabbit and rat liver cells.

Suspensions of isolated liver cells were prepared from rabbit livers perfused with Ca++-free buffer and 0.05% collagenase. Primary cell suspensions (containing both parenchymal and non-parenchymal liver cells) metabolized sulfadimidine and sulfanilamide at first-order kinetics for at least 2-3 hrs. Suspensions of purified rabbit liver parenchymal cells had an equal metabolic capacity, and it could be demonstrated that the metabolic rate of both sufadimidine and sulfanilamide was correlated to the amount of viable parenchymal cells in suspension. Suspensions of non-parenchymal cells were lacking the ability to metabolize both drugs. By means of homogenates of purified rabbit and rat liver cells, it could be demonstrated that the enzyme N-acetyltransferase was located in the cytosolic fraction of the parenchymal cells. It was concluded that the cytosolic fraction of the liver parenchymal cells is the main site of sulfonamide acetylation in both rabbit and rat.