Decrease in the expression of hepatic lipase activity following partial hepatectomy.

Variations in hepatic lipase (HL) activity were studied for the first time in liver, plasma and adrenal glands of partially hepatectomized (70%), sham-operated and intact rats. Activity profiles performed during 7 days in liver, plasma and adrenal glands of sham-operated rats were similar to those obtained in intact animals. However, HL activity in intact animals appeared to be slightly higher during the first 24 hours. Following surgery, hepatectomized animals showed a reduction of about 300 U in liver HL activity which persisted for 7 days. Plasma HL activity of hepatectomized rats was undetectable at 6 hours post-surgery but in increased afterwards. A high correlation between liver and adrenal gland HL activity was found in hepatectomized but not in sham-operated animals. HL mRNA levels in hepatectomized rats showed a 40% decrease during the first 24 hours after surgery, but they returned to the normal range later. On the other hand, HL mRNA values increased in sham-operated rats but no increase in HL activity was detected in these animals. To conclude, our results show that HL activity decreases dramatically during hepatic regeneration due to a concomitant decrement in the expression of the gene that encodes the enzyme and to other undetermined factors.