Identification of an adipose tissue-like lipoprotein lipase in perfusates of chicken liver

Abstract

The nature of the lipolytic activity released from chicken livers perfused with Krebs-Ringer buffer (pH 7.0) containing heparin (50 or 10 U/ml), fraction V albumin (3%), and glycerol (20%) was investigated. The nonrecirculating perfusates contained both previously described NaCl-resistant "liver lipase" as well as an apoLp-Gluactivated lipoprotein lipase (LPL). Crude perfusate lipolytic activity was separated on heparin-Sepharose columns into two enzymatic peaks which were eluted at mean NaCl molarities of 0.75 M (liver lipase) and 1.2 M (LPL). The liver LPL activity was stimulated 7-fold by human apoLp-Glu (half maximal activity at 1.5 microgram/ml) and inhibited by apoLp-Ala, apoLp-Ser, apoLp-GlnI, and apoLP-GlnII. Liver LPL was fully inhibited by anti-adipose LPL immunoglobulins. The "liver lipase" was not affected by apoLp-Glu (3-34 microgram/ml) or anti-adipose LPL immunoglobulins. The data demonstrate the presence in liver perfusates of a LPL with properties similar to adipose tissue lipoprotein lipase.