THE CONTRIBUTION OF HEPATOCYTES TO PROSTAGLANDIN SYNTHESIS IN RAT-LIVER

The contribution of hepatocytes to liver prostaglandin (PG) synthesis Is not clear, We compared prostaglandin synthesis in homogenates of whole liver, freshly isolated hepatocytes, and mixed non-parenchymal cells from the same rat livers, and optimized the assay, Whole liver homogenates made 27.2 +/- 7.1 mg PGE(2)/mg protein/5 min (+/- SEM, n = 4 livers), Hepatocyte homogenates made 39 +/- 9% as much PGE(2)/mg protein as did the matched whole livers, Non-parenchymal cell homogenates made sightly more PGE(2) than whole liver, but much more PGD(2). Subsequent studies showed that fresh hepatocyte suspensions contain significant contamination with non-parenchymal cells, Homogenates from ricin-purified hepatocyte monolayers made at least half as much PGE(2) as did conventional monolayers, However, taking cellular purity into account, hepatocytes must contain much less than a third of liver cyclooxygenase activity.