Abstract
The triglyceride lipase (TGL) activity of liver homogenates of mice with Sarcoma 180 was measured. The liver homogenate of normal or tumor-bearing mice was treated with 0.25% Triton X-100 and centrifuged at 100,000 g for 60 min, and the supernatant was applied to a heparin-Sepharose column. In normal mice, most of the TGL activities in the supernatant was eluted with 0.75 M NaCl from the column. In mice with Sarcoma 180, the TGL gave two peaks on heparin-Sepharose column chromatography, which were eluted with 0.75 M and 1.5 M NaCl, respectively. The activity in the first peak (0.75 M NaCl eluate) decreased; that in the second peak (1.5 M NaCl eluate) increased, and the ratio of the second peak to the first peak increased during tumor development. The livers of normal mice and mice on day 10 after tumor inoculation were perfused with heparin. The highest rate of the TGL release occurred within 1 min of heparin perfusion, and the bulk of heparin-releasable activity appeared within 2 min of perfusion in both normal and tumor-bearing mice. The TGL activity in liver perfusate of tumor-bearing mice, as well as that of liver homogenate, was resolved on a heparin-Sepharose column into two peaks, which were eluted with 0.75 M and 1.5 M NaCl, and most of the activity was eluted with 1.5 M NaCl. The nature of the TGL activity eluted from a heparin-Sepharose column was investigated. In both liver homogenates and liver perfusates, the first peak did not require serum for maximal activity and was relatively resistant to a high concentration of NaCl or protamine sulfate.(ABSTRACT TRUNCATED AT 250 WORDS)
Highlights
Ahtract The triglyceride lipase (TGL) activity of liver homogenates of mice with Sarcoma 180 was measured
We demonstrated that the hepatic T G L activity decreased and the lipoprotein lipase (LPL)-like activity increased in the livers of mice during tumor development
T h e present study demonstrates the presence of two distinct TGLs in liver homogenates and liver perfusates of mice with Sarcoma 180
Summary
Materials Tri[1-'4C]oleoylglycerol (30-60 mCi/mmol) and ACS-I1 were purchased from Amersham, Arlington. A kit for radioimmunoassay of plasma immunoreactive insulin was obtained from Dainabot, Tokyo, Japan. Kits for the triglyceride C II-test and cholesterol B-test were purchased from Wako Pure Chemicals, Ltd., Osaka, Japan. T h e initial inoculum of Sarcoma 180 tumor cells was obtained from Drs G. Sarcoma 180 cells were harvested 10 days after inoculation and centrifuged at 400 g a t 4°C for 5 min. T h e cells were suspended in an equal volume of ice-cold solution of 0.25 M sucrose, 10 mM Tris-HCI, 1 mM EDTA (pH 7.4) and disrupted by sonication at 0°C in an ultrasonic disruptor (model UR-200P, Tomy Seiko Co., Ltd., Tokyo) at position 4 for four 10-sec periods
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